Dynamics of lattice pinned charge stripes

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扭曲分子内电荷转移的英文全称

扭曲分子内电荷转移的英文全称The phenomenon of charge transfer within molecules can be quite complex, and when it occurs in a distorted manner, itis referred to as "Torsional Charge Transfer" in thescientific community.This process involves the movement of electrons from one part of a molecule to another, often resulting in a change in the molecule's overall charge distribution. It plays apivotal role in various chemical reactions and the behavior of materials.Torsional Charge Transfer is characterized by therotation of certain molecular bonds, which can lead to an altered electronic structure. This can be observed in many organic compounds and is studied extensively in the field of quantum chemistry.Understanding the mechanisms of Torsional Charge Transfer is crucial for the development of new materials with specific electronic properties, such as semiconductors and organic conductors.In molecular systems, the degree of distortion and the subsequent charge transfer can significantly influence the molecule's reactivity and stability. Researchers are continuously exploring the relationship between these factors to enhance our knowledge of molecular interactions.The study of Torsional Charge Transfer also has implications in the design of pharmaceuticals, where the electronic properties of drug molecules can affect their efficacy and safety.Moreover, this concept is not limited to organic chemistry; it is also applicable in the realm of inorganic compounds, where the transfer of charges can lead to unique physical and chemical properties.In summary, Torsional Charge Transfer is a fundamental concept in chemistry that helps us understand the behavior of molecules under various conditions and contributes to advancements in material science and pharmaceuticals.。

物理专业英语词汇P

物理专业英语词汇(P) p i n diode p i n 极管p i n junction p i n 结p n i p transistor p n i p 晶体管p n junction p n 结p n p j unction p n p 结p n p n junction p n p n 结p n p n transistor p n p n 晶体管p p junction p p 结p type semiconductor p 型半导体p wave p 波pachymeter 测厚计packing 填塞packing effect 聚集效应packing fraction 聚集率packing loss 聚集效应padua model of the nucleon核子的帕多瓦模型pair 偶pair annihilation 偶湮没pair correlation function 对相关函数pair creation 偶产生pair interaction 偶相互酌pair potential 对势pair production 偶产生pairing energy 对能pairing interaction 偶相互酌pairing rotation 对转动pairing vibration 对振动palaeo astrobiology古天体生物学palaeomagnetism 古地磁学palaeovolcanology 古火山学paleobiogeochemistry古生物地球化学palladium 车钯panalyzor多能分析仪panofsky ratio 帕诺夫斯基比panoramic lens 全景镜头panoramic telescope 全景望远镜paper capacitor 纸电容器paper chromatography 纸色谱法para state 仲态para statistics 仲统计法parabola抛物线parabolic antenna 抛物面天线parabolic curve 抛物曲线parabolic orbit抛物线轨道parabolic potential 抛物线势parabolic reflector抛物面反射器parabolic type 抛物型paraboloid 抛物面paraboloid of revolution 回转抛物面paracrystal 仲晶paradox 佯谬parahelium 仲氦parahydrogen 仲氢parallactic angle 视差角parallactic ellipse 视差椭圆parallactic motion 视差动parallax 视差parallel circuit 并联电路parallel connection 并联parallel cut y 切割parallel displacement 平行位移parallel plate capacitor 平行板形电容器parallel plate condenser 平行板形电容器 parallelogram of forces 力平行四边形 paramagnet 顺磁体paramagnetic absorption 顺磁性吸收paramagnetic element 顺磁性元素paramagnetic material 顺磁物质paramagnetic relaxation 顺磁弛豫paramagnetic resonance 顺磁共振paramagnetic resonance absorption 顺磁共振吸收paramagnetic substance 顺磁物质paramagnetic susceptibility 顺磁磁化率paramagnetism 顺磁性paramagnon顺磁振子parameter 参量parameter of state 态变数parametric amplifier 参量放大器parametric excitation 参量激发parametron 参数器parasitic ferromagnetism 寄生铁磁性parasitic oscillation 寄生振荡parasitic resonance 寄生共振paraterm 仲项paraxial rays近轴光线parent element 母元素parent mass peak 原始峰parent peak 原始峰parhelium 仲氦parity宇称parity conservation law 宇称守恒律parity violation宇称不守恒parsec秒差距partial dislocation 分位错partial equilibrium 部分平衡partial polarization 部分偏振partial pressure 分压partial wave 分波partial wave analysis 分波分析partial wave expansion 分波展开partially conserved axial vector current 轴矢量分守恒partially polarized light 部分偏振光particle 粒子particle acceleration 粒子加速particle accelerator 粒子加速器particle antiparticle conjugation 正反粒子共轭particle aspect of matter 物质的粒子观点particle beam 粒子束particle booster 注入加速器particle collisions 粒子碰撞particle concentration 粒子浓度particle counter 粒子计数器particle hole interaction 粒子空穴相互酌particle hole theory粒子空穴理论particle hole transformation 粒子空穴变换particle particle correlation 粒子粒子相关particle separation 粒子分离particle separator 粒子分离器particle track detector粒子径迹探测器particle transfer reaction 粒子转移反应partition function 统计和parton model部分子模型pascal 帕pascal,s principle 帕斯卡原理paschen back effect帕邢巴克效应paschen runge mounting 帕邢朗格装置paschen series 帕邢系passive electric circuit 无源电路passive network 无源网络passive state 被动状态passivity被动状态path路径path difference 程差path integral路径积分path of vision 视线path tracking星艮踪飞行轨道pattern 图形pattern recognition 图样识另ljpatterson function 帕特森函数patterson method帕特森方法pauli approximation 泡利近似pauli exclusion principle 泡利不相容原理pauli matrix 泡利矩阵pauli paramagnetism 泡利顺磁性pauli principle泡利不相容原理pauli spinor泡利旋量pauli villars regularization 泡利维拉斯正规化pavo孔雀座peak 峰peak energy峰值能量峰peak power峰值功率peak voltage 峰压pearl necklace model珍珠颈挂式模型peculiar galaxy 特殊星系peculiar minor planet 特殊小行星pegasus飞马座peierls potential 佩尔斯势peierls transition 佩尔斯跃迁pellet compression 靶丸压缩pellet implosion 靶丸爆聚pellets 靶丸peltier effect珀耳帖效应pencil 束pencil beam survey 深巡天pencil of light 光束pendular oscillation 摆振动pendulum 摆pendulum clock 摆钟penetrability 贯穿性penetrating power 贯穿本领penetrating shower 贯穿簇射penetration depth 穿透深度penetration depth of london 伦敦穿透深度penetrometer 透度计penning discharge 彭宁放电penning effect 彭宁效应penning gage 彭宁真空计penning ion source 彭宁离子源penning ionization 彭宁电离penrose diagramm彭罗斯图形penrose lattice彭罗斯点阵penrose tile彭罗斯点阵pentagonal prism 五角棱镜pentane lamp 戊烷灯pentode五极管pentration 贵穿penumbra 半影percent百分率percolating network 渗透网络percolation 渗滤percussion 冲击perfect conductivity 理想导电性perfect conductor 理想导体perfect cosmological principle 完全宇宙原理perfect crystal 理想晶体perfect diamagnetism 理想抗磁性perfect elasto plastic body 完全弹塑性体perfect fluid 完全铃perfect gas理想气体perfect liquid 理想液体perfect polarization 全极化perfect solution 理想溶液perfectly black body 绝对黑体perfectly elastic body 完全弹性体perfectly elastic collision 完全弹性碰撞perfectly inelastic collision 完全非弹性碰撞 period 周期period luminosity relation 周期光度关系period of oscillation 振荡周期period of revolution 公转周期periodic comet 周期彗星periodic error 周期误差periodic law 周期律periodic motion 周期运动periodic orbit 周期轨道periodic potential 周期势periodic system 周期系periodic table 周期表periodic zone 周期带peripheral collision 边缘碰撞peripheral reaction 圆周反应peripheral vision 周边视觉periscope潜望镜permalloy坡莫合金permanent magnet 永磁铁permeability 磁导率permeameter 磁导计permeance 磁导permissible dose 容许剂量permissible error 容许误差permissible stress 容许应力permissible tolerance 容许剂量permitted line 容许谱线permittivity介电常数permutation 排列permutation group 置换群permutation operator 置换算符perovskite structure 钙钛矿型结构perpendicular band 正交带perpendicular susceptibility 垂直磁化率perpetual mobile 永恒机关perpetual motion 永恒运动perpetuum mobile 永动机perpetuum mobile of the first kind 第一类永动机perpetuum mobile of the second kind 第二类永动机perseus英仙座persistence of vision 视觉暂留persistent current 持久电流persistent line 暂留谱线personal computer 个人计算机personal error 人为误差personal monitor 个人剂量计personal monitoring 个人监测perturbation 微扰perturbation energy 微扰能perturbation method 摄动法perturbation theory 微扰理论perturbed motion 受摄运动perveance电子管导电系数peta拍它petra正负电子串列存储环型加速器petrapfund series 芬德系phantom人体模型phase相位phase advance capacitor 相位超前电容器phase angle 相位角phase average 相平均phase boundary 相界phase coherent state 相位相干态phase conjugate interferometry 相位共轭干涉法phase contrast 相衬phase contrast method 相衬法phase contrast microscope 相衬显微镜phase diagram 平衡图phase difference 相位差phase discriminator相位鉴别器鉴相器phase displacement 相移phase distortion 相位畸变phase equilibrium 相平衡phase grating相位衍射光栅phase hologram相位全息图phase locked loop 锁相环路phase locking 锁相phase locking technique 锁相法phase margin 相位容限phase matching 相位平衡phase meter 功率因数计phase mode 相位模phase modulation 掂phase orbit 相轨道phase oscillation 相位振动phase retrieval 相位复原phase rule 相律phase sensitive detection 相敏检波phase separation 相分离phase shift 相移phase shift oscillator 相移振荡器phase shifter 移相器phase space 相宇phase space average 相平均phase stability相位稳定性phase transformation 相变phase transition 相变phase transition of the first kind 第一类相变phase transition of the second kind 第二类相变 phase transition of vacuum 真空相变 phase velocity 相速度phase voltage 相电压 phase volume 相体积 phason起伏量子 phasotron稳相加速器 phenomenon 现象 phoenix凤凰座 phon 方phonometer 声响度计 phonon声子 phonon drag 声子曳弓I phonon echo 声子回波 phonon excitation 声子激发phosphor磷光体 phosphorescence 磷光 phot辐透photo acoustic spectroscopy 光声光谱学 photo magnetoelectric effect 光磁电效应 photoacoustics 光声学 photoactivation 光激活 photobiology光生物学photocathode光电阴极 photocell光电池 photoceram光敏玻璃陶瓷 photochemical reaction 光化反应photochemical system 光化学系统 photochemistry 光化学photochromic glass 光变色玻璃 photocolorimeter 光电比色计 photoconduction 光电导 photoconductive cell 光电导管 photoconductive effect 内光电效应photoconductivity 光电导性 photocurrent 光电流photodensitometer 光密度计 photodensitometry光密度分析法 photodetachment 光致脱离 photodetector 光探测器photodiode光电二极管 photoeffect光电效应photoelastic effect 光弹性效应 photoelastic holography 光弹性全息照相 photoelasticimeter光致弹性测量计 photoelasticity 光弹性photoelectret 光永电体photoelectric absorption 光电吸收 photoelectric cell 光电池 photoelectric current 光电流 photoelectric effect 光电效应 photoelectric emission 光电发射photoelectric microphotometer 光电测微光度计photoelectric photometer 光电光度计 photoelectric photometry 光电测光 photoelectric pyrometer 光电高温计 photoelectric threshold 光电阈 photoelectric tube 光电管 photoelectricity 光电 photoelectromagnetic effect 光电磁效应 photoelectron 光电子 photoelectron spectroscopy 光电子谱学 photoemission 光电发射photoexcitation 光激发 photofission光核裂变photogalvanic effect 光生伏打效应 photographicapparatus 照相机 photographic camera 照相机photographic density 照相密度 photographic emulsion 照相乳胶 photographic film 软片 photographic lens 照相物镜 photographic magnitude 照相星等 photographic material 照相材料 photographic photometry 照相测光学photographic plate 照相底板 photographic telescope 天体照相机 photography 照相术 photogun光电子枪photoionization 光致电离 photoirradiation 光致辐照photoluminescence 光致发光 photolysis 光解酌photomagnetic effect 光磁效应 photometer 光度计photometric cube 光度计立方体 photometric distance 测光距离 photometric elements 测光要素 photometric quantity 光度量 photometric standard 光度学标准photometric unit 光度单位 photometric wedge 测光楔photometrical paradox 奥伯斯佯谬 photometry 光度学photomicrograph显微镜照片 photomicroscopic 显微照相机 photomultiplier光电倍增管 photomultiplier tube 光电倍增管 photon光子photon counting method 光子计数法 photon coupled pair 光导发光元件 photon echo 光子回波photon gas 光子气体 photon packet 光子束photonegative effect 负光电效应 photoneutron 光中子photonuclear fission 光核裂变 photonuclear reaction 光核反应 photophoresis 光致迁动 photopic vision 亮视觉 photoplate照相底板 photoradiometer 光辐射计photorecorder自动记录照相机 photoresist光致抗蚀剂photosemiconductor 光半导体 photosensitive resin 光敏尸 photosensitivity 光灵敏度 photosensitization 光敏化 photosphere 光球photostatistics光子统计学 photosynthesis 光合酌phototelegraphy 传真photothermal displacement 光照位移 phototransistor光电晶体管 photovisual magnitude 仿视星等 photovoltaic effect光生伏打效应 physical chaos 物理混沌 physical chemistry 物理化学 physical constant 物理常数physical double star 物理双星 physical libration 物理天平动 physical mathematics 物理数学 physical oceanography 海洋物理学 physical optics 物理光学physical pendulum 复摆physical photometer 物理光度计physical photometry 物理光度学physical property 物理性质physical quantity 物理量physical roentgen equivalent 物理伦琴当量physical variable 物理变星physicist物理学家physico chemical物理化学的physics物理学physics of heat 热物理学physics of metals金属物理学physiological acoustics 生理声学pi bond 键pi electron 电子pi electron approximation 电子近似pi meson 介子pi orbital 轨道pick up reaction 拾取反应pico微微picofarad微微法picosecond 微微秒picosecond laser微微秒激光器picosecond light pulse 微微秒光脉冲picosecond spectroscopy 微微秒光谱学pictor绘架座pid action比例积分微分酌pierce type crystal oscillator 皮尔斯石英振荡器pierce type electron gun 皮尔斯电子枪piezo ceramic element 压电陶瓷元件piezo semiconductor transducer 压电半导体换能器piezoceramics 压电陶瓷piezochromism 受压变色piezoelectric 压电piezoelectric actuator 压电传动装置piezoelectric axis 压电轴piezoelectric constant 压电常数piezoelectric crystal 压电晶体piezoelectric effect 压电效应piezoelectric element 压电元件piezoelectric loudspeaker 压电扬声器piezoelectric modulus 压电模量piezoelectric oscillator 压电振荡器piezoelectric polaron 压电极化子piezoelectric transducer 压电转换器piezoelectric vibration 压电振动piezoelectricity 压电piezometer液体压力计piezoresistor压电电阻器piezotropy 压性pile反应堆pile oscillator 反应堆振荡器pile up effect脉冲堆积效应pilot lamp指示灯pinch effect箍缩效应pinching自压缩pinhole camera针孔照相机pinning 锁住pinning center 锁住中心pinning force 锁住力pinning potential 锁住势pion介子pion beam 介子束pion condensation 介子凝聚pionic atom 介原子pionization介子化过程pipe导管pipe line 导管pippard equation皮帕德方程pirani gage 皮拉尼压力计pisces双鱼座piscis austrinus 南鱼座pitot tube皮托管planar transistor 平面晶体管planck mass普朗克质量planck time普朗克时间planck's constant 普朗克常数planck's function 普朗克函数planck's fundamental length 普朗克基本长度planck's law of radiation 普朗克辐射定律plane concave lens 平凹透镜plane convex lens 平凸透镜plane fault 面缺陷plane grating平面光栅plane mirror 平面镜plane of incidence 入射面plane of polarization 偏光面plane of projection 射影平面plane of symmetry 对称面plane polarization 平面偏振plane polarized light 平面偏振光plane polarized wave 平面偏振波plane wave 平面波planet行星planetarium 天象仪planetary aberration 行星光行差planetary cosmogony 行星演化学planetary geology 行星地质学planetary nebula行星状星云planetary system 行星系planetesimal theory 星子论planetesimals 星子planetoid小行星planimeter 测面仪plano concave lens 平凹透镜plano convex lens 平凸透镜plano cylindrical lens 平圆柱透镜plano spherical lens平面球面透镜plasma等离子体plasma accelerator 等离子体加速器plasma balance等离子体平衡plasma cluster 等离子粒团plasma confinement等离子体禁闭plasma containment等离子体禁闭plasma diagnostics等离子体诊断学plasma dispersion function等离子体弥散函数plasma echo等离子体回波plasma engine等离子体发动机plasma focus等离子体聚焦点plasma frequency 等离子体频率plasma gun等离子体枪plasma heating等离子体加热plasma instability等离子体不稳定性plasma membrane 原生质膜plasma oscillation等离子体振荡plasma physics等离子体物理学plasma potential等离子体势plasma source等离子体源plasma wave等离子体波plasmapause等离子体层顶plasmasphere等离子层plasmoid等离子粒团plasmon等离振子plasmon excitation等离振子激发plastic anisotropy 塑性蛤异性plastic deformation 塑性变形plastic flow 塑性怜plastic material 塑胶plastic potential 塑性势plastic wave 塑性波plastic yield塑性屈服plasticity 塑性plastics 塑胶plate正极plate battery阳极电池组plate circuit板极电路plate current 板极电流plate detection 板极检波plate resistance 板极电阻plate tectonics 板块构造plate voltage板极电压plateau 坪platinum 铂platinum group elements 铂族元素platinum resistance thermometer 铂电阻温度计pleochroic halo 多向色晕pleochroism 多色性pleochromatism 多色性plk method plk 法plot标绘plotter标绘器plug插头plural scattering 多重散射plus 加plus sign 加口号pluto冥王星plutonium 钵plutonium reactor 钚堆plutonium regeneration 钵再生pluviometer 雨量器pneumatic laser气动激光器pockels cell波克尔斯盒pocket dosimeter袖珍剂量计pocket of air 气囊point at infinity 无穷远点point charge 点电荷point contact rectifier 点接触整流point contact transistor 点接触晶体管point defect 点缺陷point discharge 尖端放电point group 点群point lattice 点晶格point of action 酌点point of application 酌点point of contact 接触点point source of light 点光源poise 泊poiseuille flow 泊萧叶怜poiseuille,s law泊萧叶定律poisson bracket 泊松括号poisson equation 泊松方程poisson process 泊松过程poisson,s ratio 泊松比polar aurora 极光polar binding 极性键polar bond极性键polar cap 极冠polar cap absorption 极冠吸收polar crystal极性晶体polar gas极性气体polar light 极光polar liquid极性液体polar molecule 极性分子polar motion 极运动polar sequence 北极星序polar telescope 天极仪polar triangle 极三角形polar vector 极矢量polar wandering 极运动polar year 极年polarimeter 偏振计polarimetry测偏振术polaris北极星polarisation angle布儒斯特偏振角polariscope偏振光镜polariton电磁耦合振子polarity 极性polarizability 极化率polarizability ellipsoid 极化率椭球polarization 极化polarization charge 极化电荷polarization current 极化电流polarization curve 极化曲线polarization factor 极化因数polarization filter 偏振滤光镜polarization force 极化力polarization interferometer 偏振干涉仪polarization microscope 偏光显微镜polarization of neutron 中子的极化polarization orbital 极化轨道polarization potential 极化势polarization spectroscopy 偏振光光谱学polarized beam 极化束polarized ion source 极化离子源polarized light 偏振光polarized neutron diffraction technique 极化中子衍射法polarized nucleus 极化核polarized raman scattering 偏振喇曼散射polarized relay极化继电器polarized target 极化靶polarizer起偏器偏振器polarizing filter 偏振滤光镜polarizing microscope 偏光显微镜polarizing prism 偏振棱镜polarograph 极谱仪polarography 极谱学polaroid偏光片polaron极化子pole 极pole of ecliptic 黄极pole piece 极片pole shoe 极片pole strength磁极强度polestar北极星polhode心迹线polishing 抛光poloidal magnetic field 极向磁场polonium 车卜polyatomic molecule 多原子分子polycondensation 缩聚酌polycrystal 多晶polycrystalline material 多晶物质polydisperse system 多色散系polygon of forces 力多边形polygonization 多边形化polymer聚合物polymer complex聚合络合物polymer crystal 聚合晶体polymer effect 聚合效应polymerization 聚合polymerization of protein 蛋白质聚合polymolecularity 多分子性polymorphism 多形性polyphase 多相polyphase current 多相电流polytrope多变性polytropic change多方状态变化polytropic index 多方指标polytropic process 多变过程pomeranchuk effect坡密朗丘克效应pomeranchuk theorem坡密兰丘克定理pomeron坡密子pool type reactor 池式堆population 全域population inversion 粒子数反转pore小黑子porosity多孔性porous flow 多孔流position 位置position resolution 位置分辨率position sensitive detector对位置灵敏的探测器position vector 位置矢量positive 正片positive charge 正电菏positive column 阳极区positive crystal 正晶体positive electricity 正电positive electrode 阳极positive electron 正电子positive element 正元素positive eyepiece 正目镜positive feedback 正反馈positive hole 空子positive ion 阳离子positive lens 正透镜positive magnetostriction 正磁致伸缩positive meniscus 凹凸透镜positive meson 正介子positive rays 阳射线positon正电子positron正电子positron annihilation 正电子湮没positron beam 正电子束positron channeling 正电子沟道positron electron annihilation 偶湮没positron electron tandem ring accelerator 正负电子串列存储环型加速器petrapositron emission 正电子发射positron factory 正电子工厂positron spectroscopy 正电子谱学positronium电子偶素post newtonian approximation 后牛顿近似post nova燃后新星post post newtonian approximation 后后牛顿近似potassium 车甲potassium dihydrogenphosphate 磷酸二氢钾potential 势potential barrier 势垒potential difference 势差potential divider 分压器potential energy 势能potential energy curve 势能曲线potential field 势场potential flow 势流potential function 势函数potential instability 对粱稳定性potential motion 势运动potential scattering 势散射potential well 势阱potentiometer 电位计potts model波特模型pound 磅powder camera粉末照相机powder diffraction method 粉末法powder pattern粉末干涉象powder photography 粉末照相术power功率power amplification 功率放大power demonstration reactor 动力示范堆power density 功率密度power dissipation 耗散功率power factor 功率因数power factor meter 功率因数计power gain功率增益power of a lens透镜的焦强power reactor 动力堆power tube 功率管poynting robertson effect坡印廷罗伯逊效应poynting,s vector 坡印廷矢量practical system of units 实用单位制prandtl number 普朗特数praseodymium 错pre vacuum初真空pre vacuum pump 预备真空泵preacceleration 预加速preaccelerator 前加速器preamplifier前置放大器precession 旋进precession camera 旋进照相机precession of orbit 轨道旋进precessional constant 岁差常数precious metal 贵金属precipitation 沉淀precision精密度precision measurement 精密测量predict earthquake with catfish 用鲶鱼预报地震prediction 预报prediction of solar activity 太阳活动预告predissociation 预离解preferential recombination 优选复合preionization 预电离preliminary vacuum 初真空pressure 压力pressure broadening 压力增宽pressure coefficient 压力系数pressure dispersion 压力弥散pressure drag 压力阻pressure drop 压降pressure gage 压力表pressure head 压头pressure height equation 气压测高公式pressure of light 光压pressure of water vapor 水汽压pressure sensitive diode 压力敏感二极管pressure sensitive transistor 压力敏感晶体管pressure tensor 压强张量pressurized air 压缩空气pressurized water reactor 压水堆primakoff effect普里马科夫效应primary battery 原电池primary beam初级束流原射线束primary cell 原电池primary circuit 原电路primary colors 原色primary cosmic radiation 原宇宙辐射primary cosmic rays 原宇宙射线primary electron 原电子primary energy 一次能量primary ionization 一次电离primary rainbow 昼primary recrystallization 一次再结晶primary standard 原标准primary star 智primary target 初始靶primary thermometer 初始温度计primary voltage 初级电压prime meridian 零子午线prime vertical 卯酉圈primeval galaxy 原始星系primitive black hole 原始黑洞primitive lattice 初基点阵primordial solar nebula 太阳系星云principal axes of stress 应力轴principal axis 轴principal axis of inertia 惯性轴principal index for extraordinary ray 非常光线舟射率principal moment of inertia 矢口动惯量principal plane 纸面principal point 帚principal quantum number 挚子数principal ray 肘线principal refractive indices 舟射率principal series 诌系principal stress 枝力principle 原理principle of constancy of light velocity 光速不变原理principle of corresponding states 对应态原理principle of detailed balancing 细致平衡原理principle of entropy compensation 熵补偿原理principle of equal a priori probabilities 等验前概率原理principle of equipartition 均分原理principle of equivalence 等价原理principle of equivalence of mass and energy 质能当量原理principle of indeterminancy 测不准原理principle of least action 最小酌原理principle of least constraint 最小约束运动原理principle of microscopic reversibility 微观可逆性原理principle of minimum dissipation of energy 最小能量耗散原理principle of relativity 相对性原理principle of reversibility 可逆性原理principle of superposition 叠加原理principle of virtual displacement 虚位移原理principle of virtual work 虚功原理printed board印刷电路板printed circuit 印刷电路printer打印机prism棱镜prism angle 棱镜角prism spectrograph 棱镜摄谱仪prism spectroscope 棱镜分光镜prismatic transit instrument 折轴中星仪probability 概率probability current density 概率淋度probability density 概率密度probability distribution 概率分布probability distribution function 概率分布函数probability function 概率函数probability of collision 碰撞概率probable error 概率误差probe探头probe charge试探电荷probe method 探测法problem of three bodies 三体问题process control 过程控制product nucleus 生成核production 产生production of entropy 熵产生profile drag翼型阻力profile monitor剖面监测器prognosis 预报program 程序program library 程序库programme 程序programming language 程序设计语言progressive wave 前进波projecting lens 投影透镜projection 投影projection of crystal 晶体投影projection operator 投影算符projector投影器幻灯promethium 专钷prominence 日珥prominence spectroscope 日珥分光镜prompt neutron 瞬发中子propagation 传播propagation constant 传播常数propagation of sound 声传播propagation velocity 传播速度propagator传播函数proper channeling 本盏道proper field 固有场proper lorentz group 固有洛伦兹群proper motion 自行proper time 原时proper tone 固有音proper value 本盏proportion 比例proportional component 比例分量proportional counter 正比计数管proportional ionization chamber 正比电离室proportionality factor 比例系数protoatmosphere 原大气protocol 协议proton质子proton accelerator 质子加速器proton antiproton collision 质子反质子碰撞proton decay 质子衰变proton induced x ray analysis 质子激发 x 射线分析proton linear accelerator 质子直线加速器proton number 质子数proton spectrometer 质子谱仪proton synchrotron质子同步加速器protoplanet 原行星protostar原恒星protosun原太阳prototype 原型prototype meter 米原器proximity 附近proximity effect 邻近效应proximity switch 接近开关pseudo crossing 伪交叉pseudo crystal 伪晶体pseudo dipole interaction 伪偶极子相互酌pseudo energy gap 伪能隙pseudo equilibrium 伪平衡pseudo image 假象pseudo plastic flow 伪塑性流pseudo scalar 伪标量pseudo scalar coupling 伪标量耦合pseudo scalar meson 伪标介子pseudo tensor 伪张量pseudo vector 伪矢量pseudo vector coupling 伪矢量耦合pseudo wave 伪波pseudopotential 伪势pseudostate 伪态pseudosymmetry 伪对称pseudovariable 准变星pss method pss 法psychoacoustics 心理声学psychobiophysics心理生物物理学psychorheology 心理龄学psychrometer 干湿表ptolemaic system托勒玫体系pulsar脉冲星pulsating current 脉动电流pulsating star 脉动星pulsating universe 振动宇宙pulsating variable 脉动星pulsating voltage 脉动电压pulsation 脉动pulse脉冲pulse amplifier 脉冲放大器pulse code modulation 脉冲编码灯pulse coincidence 脉冲符合pulse decay脉冲衰减pulse discharge 脉冲放电pulse duration脉冲持续时间pulse generator脉冲发生器pulse height脉冲高度pulse height analyzer脉冲高度分析器pulse height discriminator 脉冲高度鉴别器pulse height selector脉冲高度选择器pulse interval 脉冲间隔pulse laser脉冲激光pulse length脉冲宽度pulse modulation 脉冲灯pulse motor脉冲电动机pulse neutron source脉冲式中子源pulse oscillator脉冲发生器pulse recurrence frequency 脉冲重复频率pulse repetition frequency 脉冲重复频率pulse shape脉冲波形pulse shape discriminator 脉冲波形鉴别器pulse shaper脉冲成形器pulse shaping脉冲成形pulse spacing脉冲间隔pulse transformer 脉冲变压器pulse width脉冲宽度pulse x rays脉冲x射线pulsed cyclotron脉冲回旋加速器pulsed ion source脉冲离子源pulsed neutron beam 脉冲中子束pulsimeter脉冲计数器pump 泵pumping 抽运pumping speed 抽速punctum remotum 远点pupil光瞳pupillary aperture 光瞳孔径puppis船尾座pure scattering 纯散射pure state 纯态pure tone 纯音purgemeter微量量计purity纯度purple light 柴光push button 按钮push pull推挽式push pull amplifier 推挽放大器pycnometer 比重瓶pyrex glass派热克斯玻璃pyrgeometer地面辐射表pyrheliometer直接日射强度计pyroelectricity 热电pyrogeology 火山学pyrology 热学pyromagnetism 高温磁学 pyrometer高温计 pyrometric cone 测温锥 pyrometry 高温测定法 pyxis罗盘座。

Deposition dynamics of Na monomers and dimers on an Ar(001) substrate

∗ Corresponding author Email-address : dinh@irsamc.ups-tlse.fr
Preprint submitted to Elsevier
and aim here at a theoretical study of deposition of Na on a rare gas surface. Thereby we concentrate on the ﬁrst stages of growth, the capture of atoms and molecules with particular emphasis on charged projectiles.
2. Model
We start with a very brief summary of the hierachical description of the combined NaAr system. We treat the metal atoms in full microscopic detail at the level of Time Dependent Local Density Appromixation (TDLDA) for the valence electrons, coupled to Molecular Dynamics (MD) for the ions. Details on the successful TDLDA-MD approach for free clusters can be found in [28,29]. The substrate consists out of Ar atoms to which we associate classical degrees of freedom for position and dipole moment. The latter serves to take into account the dynamical polarizability of the substrate. The Ar atoms are coupled to the Na by long range polarization and some short range repulsion to account for the Pauli blocking of cluster electrons in the vicin-

翻译

高聚物的固态流变行为G. W. HALLDIN” and Y. C. LOf威斯康辛·麦迪逊大学，机械工程学院。

威斯康辛，麦迪逊 53 706高聚物的固态流变行为在力学行为表现，测试，固态成形中十分重要。

这篇文章包含了一些非常有经济利用价值的高聚物的固态流变曲线，研究了固定型半晶态，可导型半晶态，可导型无定形态，两相无定形态树脂的拉伸，压缩过程。

半结晶态高聚物出现几何级的负荷下降，无定形态高聚物出现了线性应变软化，并使用了覆盖全部应力范围的流动学方程，对全部材料进行了应变软化的模拟。

简介对于高聚物科学来说，一个对热塑性塑料固态流动完全实际的理解和模拟是十分重要的。

这种行为经常在材料评价中出现，对固态成形十分重要[1-5]。

这种技术使用固态流动成形，能够成形超高分子量聚合物[6,7]。

固相流动的显著特征就是流动曲线，显示了应力应变的关系，所有固态研究都需要它，十分有名。

对高聚物来说，流动曲线与工程上的应力应变曲线有所不同，尤其对于半晶态，晶态，无定形热塑性塑料来说，尤为显著。

对大多数可延展，它们在弯曲时显示出应力下降，是由于“几何级的应变软化”，即不稳定的裂纹向内增生的速度，大于应力紧缩的速度。

工程应力减小的时候，真应力却在直线上升，Vincent[8]解释说，负荷下降是由于几何级的应变软化，Marshall和Tompson[9]用热压实验试图解释这种现象。

建于移动变形基础上的金属变形理论早已成熟，在很多情况下可被验证到，对高聚物来说，Imada，et al[l0]假设了三种机理：即α1，α2，β机理,Vincent[8]认为，屈服是由于相连接高分子链断裂形成的，无论无定形高分子之间的交错和二价力的作用。

有些理论建于自由体积[l1]和玻璃化转变温度[l2]之上，却无理论可以将半晶态高聚物和无定形高聚物与真应力联系起来。

Bahadur[13]做了一个流动曲线特征分析，发现PVC、PVDC的屈服点，但PE，PA66，PC，PTFE 却没有，Imada，et al[14]发现真应力升的很快，Brown和Ward[15]也发现了PE在剪切作用下拉伸变形应力下降。

半导体物理与器件——Terms汉译英

半导体物理与器件——Terms(术语)U1 Terms:Semiconductor physics and devices半导体物理与器件,Space lattice空间晶格, unit cell晶胞, primitive cell原胞,basic crystal structures 基本晶格结构(five), Miller indices密勒指数, atomic bonding原子价键U2 Terms:quantum mechanics量子力学,energy quanta能量子, wave-particle duality波粒二象性,the uncertainty principle测不准原理/海森堡不确定原理Schrodinger's wave equation薛定谔波动方程, eletrons in free Space自由空间中的电子the infinite potential well无限深势阱, the step potential function 阶跃势函数, the potential barrier势垒.U3 Terms:Pauli exclusion principle泡利不相容原理, quantum state量子态. allowed energy band允带, forbidden energy band禁带.conduction band导带, valence band价带,hole空穴, electron 电子.effective mass有效质量.density of states function状态密度函数,the Fermi-Dirac probability function费米-狄拉克概率函数,the Boltzmann approximation波尔兹曼近似,the Fermi energy费米能级.U4 Terms:charge carriers载流子, effective density of states function有效状态密度函数,intrinsic本征的,the intrinsic carrier concentration本征载流子浓度, the intrinsic Fermi level本征费米能级.charge neutrality电中性状态, compensated semiconductor补偿半导体, degenerate简并的,non-degenerate非简并的, position of E F费米能级的位置U5 Terms:drift current漂移电流, diffusion current 扩散电流,mobility迁移率, lattice scattering晶格散射, ionized impurity scattering 电离杂质散射, velocity saturation饱和速度,conductivity电导率,resistivity电阻率.graded impurity distribution杂质梯度分布,the induced electric field感生电场, the Einstein relation爱因斯坦关系, the hall effect霍尔效应U6 Terms:nonequilibrium excess carriers非平衡过剩载流子,carrier generation and recombination载流子的产生与复合,excess minority carrier过剩少子,lifetime寿命,low-level injection小注入,ambipolar transport双极输运, quasi-Fermi energy准费米能级.U7 Terms:the space charge region空间电荷区,the built-in potential内建电势, the built-in potential barrier内建电势差,the space charge width空间电荷区宽度, zero applied bias零偏压, reverse applied bias反偏, onesided junction单边突变结.U8 Terms:the PN junction diode PN结二极管, minority carrier distribution少数载流子分布, the ideal-diode equation理想二极管方程, the reverse saturation current density反向饱和电流密度.a short diode短二极管,generation-recombination current产生-复合电流,the Zener effect齐纳效应, the avalanche effect雪崩效应, breakdown击穿.U9 Terms:Schottky barrier diode (SBD)肖特基势垒二极管,Schottky barrier height肖特基势垒高度.Ohomic contact欧姆接触,heterojunction异质结, homojunction单质结,turn-on voltage开启电压,narrow-bandgap窄带隙, wide-bandgap宽带隙,2-D electron gas二维电子气U10 Terms:bipolar transistor双极晶体管,base基极, emitter发射极, collector集电极.forward active region正向有源区, inverse active region反向有源区, cut-off截止, saturation饱和,current gain电流增益,common-base共基, common-emitter共射.base width modulation基区宽度调制效应, Early effect厄利效应, Early voltage厄利电压U11 Terms:Gate栅极, source源极, drain漏极, substrate基底.work function difference功函数差threshold voltage阈值电压, flat-band voltage平带电压enhancement mode增强型, depletion mode耗尽型strong inversion强反型, weak inversion弱反型,transconductance跨导, I-V relationship电流-电压关系。

Electro-dynamics

E: electric field D: electric displacement polarization
D = ε 0E + P
B: magnetic induction H: magnetic field
H=
B
µ0
−M
magnetization
MIT 2.71/2.710 10/06/04 wk5-b-14
µ 0ε 0 ≡
1 c
2 vacuum
cvacuum: speed of light in vacuum
ε = (1 + χ )ε 0 ≡ n 2ε 0
n: index of refraction
µ 0ε =
p = q+ r+ − q−r−
Dipole moment
Polarization
P = ∑p
± ± ±
–+ –+ –+
–+ –+ –+
–+ –+ –+
– + – + – +
Spatially variant polarization induces local charge imbalances (bound charges)
MIT 2.71/2.710 10/06/04 wk5-b-3
dF
II ′ = µ0 dl 2πr
(magnetic) permeability of free space
Note the units…
⎛ Electric ⎞ 1 ⎛ Charge ⎞ ⎜ ⎟ ⎜ force ⎟ = ε ⎜ Distance ⎟ ⎠ ⎠ ⎝ 0 ⎝ ⎛ Magnetic ⎞ ⎛ Charge ⎞ ⎜ ⎟ ⎜ force ⎟ = µ 0 ⎜ Time ⎟ ⎝ ⎠ ⎠ ⎝

Phase diagram of the quarter-filled extended Hubbard model on a two-leg ladder

a r X i v :c o n d -m a t /0008068v 2 [c o n d -m a t .s t r -e l ] 9 O c t 2000Phase diagram of the quarter–ﬁlled extended Hubbard model on a two–leg ladderMatthias Vojta (a )∗,Arnd H¨u bsch (b ),and R.M.Noack (c )(a)Department of Physics,Yale University,New Haven,CT 06520–8120,USA(b)Institut f¨u r Theoretische Physik,Technische Universit¨a t Dresden,D–01062Dresden,Germany(c)Institut f¨u r Physik,Johannes–Gutenberg–Universit¨a t Mainz,D–55099Mainz,Germany(February 1,2008)We investigate the ground–state phase diagram of the quarter–ﬁlled Hubbard ladder with nearest–neighbor Coulomb repulsion V using the Density Matrix Renormalization Group technique.The ground–state is homogeneous at small V ,a “checkerboard”charge–ordered insulator at large V and not too small on–site Coulomb repulsion U ,and is phase–separated for moderate or large V and small U .The zero–temperature transition between the homogeneous and the charge–ordered phase is found to be second order.In both the homogeneous and the charge–ordered phases the existence of a spin gap mainly depends on the ratio of interchain to intrachain hopping.In the second part of the paper,we construct an eﬀective Hamiltonian for the spin degrees of freedom in the strong–coupling charge–ordered regime which maps the system onto a frustrated spin chain.The opening of a spin gap is thus connected with spontaneous dimerization.I.INTRODUCTIONQuasi–one–dimensional systems present a unique op-portunity to study the interplay between strong quantum ﬂuctuations on the one hand and a tendency to charge or spin ordering on the other.Examples include Peierls or spin–Peierls behavior as well as charge ordering due to electron–electron interaction.One material in which such behavior has been found is the two–leg ladder ma-terial NaV 2O 5.NaV 2O 5undergoes a phase transition at T c =34K that is characterized by the opening of a spin gap and a doubling of the unit cell.Although this transition was originally thought to be spin–Peierls,recent studies have found evidence for charge order.1–3Above the transition,the material seems to be best de-scribed as a quarter–ﬁlled ladder.4,5Such two–leg–ladder structures have also been found in a number of other ma-terials,including the Vanadates MgV 2O 5and CaV 2O 5,and the cuprates SrCu 2O 3and Sr 14Cu 24O 41.For a more detailed description of ladder materials and models as well as a discussion of the extensive theoretical work on ladder models,we direct the reader to a recent review 6and the references contained therein.In NaV 2O 5,the character of the charge ordering and the nature of the transition are currently under debate.While evidence is growing 7–9that the charge–ordered state has a zigzag–like charge arrangement,the ques-tion of whether this charge ordering is continuous or discontinuous has not yet been settled experimentally.Theoretically,the magnetic properties of the compound for T <T c have been calculated for diﬀerent charge–ordering patterns 10,11and compared to experiments.Again,zigzag charge ordering on ladders (possibly with intervening disordered ladders 12)leads to magnon disper-sions in good agreement with neutron scattering data.Additionally,the possibility of two separate transitions at nearby temperatures has been raised;13,14in this sce-nario the charge order would set in at one temperature while the spin gap would open at a second,lower critical T .Very recently,a scenario of singlet cluster formation instead of zigzag charge ordering has been suggested.15However,this model seems not to be able to reproduce the experimentally found spin gap and magnon disper-sion data.16It is clear that more experimental work is necessary to clarify the nature of the low–temperature phase of NaV 2O 5.One of the simplest models of interacting electrons that allows for charge ordering is the extended Hubbard model,i.e.the Hubbard model supplemented by an ad-ditional nearest–neighbor (NN)Coulomb repulsion,V .This model has been studied in one dimension (1D)in the strong–coupling limit,17at quarter ﬁlling 18,19and at half ﬁlling 20–23and in between,24,25in the 2D system at half ﬁlling,26,27and within the Dynamical Mean Field Theory (the limit of inﬁnite dimensions)at quarter 28and half ﬁlling.29A variety of techniques,such as mean–ﬁeld approximations,perturbation theory,as well as numer-ical methods as quantum Monte Carlo and the Density Matrix Renormalization Group (DMRG)have been em-ployed.The result of investigations of the charge–order tran-sition can be summarized as follows:At the mean–ﬁeld level,the transition between a homogeneous state and a charge–density wave (CDW)state at half ﬁlling in a hypercubic lattice occurs at V c =U/z 0,where z 0de-notes the number of nearest neighbors (z 0=2d )and U is the on–site interaction.Numerical studies 21,22indicate a slightly higher value of V c ,at least in 1D.Interestingly,the transition at half ﬁlling in 1D has been found to be second order at small U/t and ﬁrst order at large U/t with the tricritical point located at U c /t ∼4−6.22,23Here we use the term “ﬁrst order”to denote discontinuous behav-ior of the charge order parameter as a function of micro-scopic parameters such as V or band ﬁlling,and “secondorder”to denote continuous behavior.Forﬁllings be-low half–ﬁlling in1D,the situation is more complicated because a number of phases compete at large V.18,19,25 For dimension larger than one,indications are that the charge–order transition is generallyﬁrst order.26–29How-ever,conclusive studies that can reliably distinguish be-tweenﬁrst–and second–order transitions are lacking.At small U and large V,the extended Hubbard model un-dergoes phase separation(PS)rather than a transition to a CDW state.For the1D model between quarter–and half–ﬁlling,it has been established25that PS occurs for |U|/t<4in the V=∞limit,whereas for U/t>4the system undergoes a transition to a q=πCDW state for suﬃciently large V.24Phase separation in higher dimen-sions has also been discussed.30For the1D system in particular there has been recent interest in the possibility of dominant superconducting correlations in the uniform ground–state away from half–ﬁlling when V≫U∼t,19,25i.e.,in the proximity of the phase–separated region.We note here that the uniform phase in1D oﬀhalf–ﬁlling is metallic and can in gen-eral be described within the Luttinger–liquid picture.Al-though dominant superconducting correlations have not been established in the ground state of the1D extended Hubbard model to date,a number of non–Luttinger–liquid eﬀects have been observed.25Some of the present authors have previously studied31 the charge–order transition in the extended Hubbard model on the two–leg ladder at various bandﬁllings for U/t=4and8.A transition to a checkerboard charge–ordered state was found for allﬁllings between quarter–and half–ﬁlling.The transition is second–order near quarterﬁlling andﬁrst–order near half–ﬁlling for suﬃ-ciently large U.The focus of the present paper is on this model at quar-terﬁlling,with a two–fold purpose:First,we present a comprehensive study of the phase diagram as a function of U/t and V/t for repulsive U and V and discuss the properties of the ground state phases as well as the na-ture of the phase transitions.Second,we derive an eﬀec-tive Hamiltonian for the spin degrees of freedom in the charge ordered state at strong coupling,and compare the predictions of this eﬀective low–energy theory with our numerical results.A.Phase diagramOur main results,the phase diagrams deduced from the numerical calculations,are summarized in Figs.1 (isotropic hopping)and2(anisotropic hopping).The phases are distinguished by the presence or absence of a gap for spin and/or charge excitations.To denote this, we employ the following labeling:HI sg denotes a homo-geneous insulator(nonzero charge gap)with a spin gap, HI a homogeneous insulator without a spingap,HM sg (HM)a homogeneous metallic phase having zero charge gap with(without)spin gap,and CDW sg(CDW)is a charge–ordered state with(without)spin gap.The CDW states are always insulating in the present quarter–ﬁlled model.The phase diagrams can be roughly divided into four regions:(i)Weak coupling:for small U and V we ﬁnd homogeneous phases similar to the ones in the“bare”Hubbard model(see discussion in Sec.II and results in Sec.III B).(ii)Large U,small V:These homogeneous strong coupling phases have characteristics similar to the weak–coupling region.(iii)Small U,large V:phase sep-aration,this is discussed further in Sec.III D.(iv)Strong coupling:large U and V lead to an insulating checker-board charge–ordered with either gapless or gapped spin excitations depending on the ratio of V/U.0246810121416V / t246810121416U/tCDWPSCDW sg?HIFIG.1.Ground state phase diagram of the extended quar-ter–ﬁlled Hubbard model on a two–leg ladder with isotropic hopping,as a function of the on–site and nearest–neighbor repulsion,U/t and V/t.The phase labeling is explained in the text,the dashed lines represent second order phase tran-sitions.The solid line marks the boundary of the phase sepa-ration region(PS)where the thermodynamic compressibility diverges.For isotropic hopping we have numerically determined the phase boundaries as shown in Fig.1.The precise lo-cation of the CDW–CDW sg boundary at which the spin gap closes at intermediate coupling could not be obtained by the methods used here;we have indicated this uncer-tainty by a question mark in the phase diagram.In the case of anisotropic hopping we have not mapped out the full phase diagram,but the numerical results(dis-cussed in Sec.III)provide the schematic pictures shown in Fig.2.Varying the ratio of the rung to leg hopping strengths,t⊥/t ,has two eﬀects:(a)For small t⊥/t there appears a metallic phase(HM sg)with spin gap and dominating d–wave–like singlet pair correlations(as in the“bare”V=0Hubbard ladder).(b)The existence of a spin gap depends strongly on the hopping ratio,i.e., there is a transition as function of t⊥/t where a spin gap opens(in both the homogeneous and CDW phases).The critical hopping ratio may depend on the interaction strength,but is near unity in the homogeneous phases for reasonable values of the interactions.V / t ||||CDWPSHIt ⊥/t || > 1sgFIG.2.Proposed schematic phase diagrams for the ex-tended quarter–ﬁlled Hubbard model with (large)hopping anisotropy.The phases are labeled as before.For t ⊥<t ,the spin gap is nonzero in accordance with the weak coupling predictions,whereas for t ⊥>t the spin gap is always zero.In the former case,the spin gap can be suppressed deep in the charge–ordered phase if V /U is smaller than a critical value.The rest of the paper is organized as follows:In Sec.II,we introduce the extended Hubbard model and discuss some results known for the V =0case,i.e.,the “bare”Hubbard model on a two–leg ladder.In Sec.III,we present our numerical results,discuss the properties of the phases shown in Figs.1and 2,and examine the tran-sition to the charge–ordered state.At large V ,where charge order is well established,it is possible to derive an eﬀective Hamiltonian for the residual spin degrees of freedom;this is done in Sec.IV.A summary and a dis-cussion of the relevance of our results to experimental systems (especially NaV 2O 5)terminates the paper.II.EXTENDED HUBBARD MODELThe single–band extended Hubbard model has the HamiltonianH =−ij σt ij (c †iσc jσ+h.c.)+Uin i ↑n i ↓+ijV ij n i n j .(1)Here we consider a lattice consisting of two chains oflength L ,i.e.,a ladder,and restrict ourselves to the band ﬁlling n =N/(2L )=1/2,where N is the number of electrons.The summation ij runs over all pairs of nearest–neighbor sites on the ladder,taking open bound-ary conditions between the chains.The hopping matrix elements along the legs and rungs of the ladder are de-noted t and t ⊥,respectively,and the nearest–neighborCoulomb interactions are similarly denoted V and V ⊥.Unless otherwise noted,we will use t as unit of energy.In this work,we will treat primarily the “isotropic”case,t =t ⊥=t and V =V ⊥=V .The non–interacting Hamiltonian (U =V =0)can be diagonalized by a Fourier transform (for periodic bound-ary conditions in the chain direction),leading to the single–particle energiesǫq =−2t cos q x +t ⊥cos q y(2)where q =(q x ,q y ),q x is the momentum along the chains and the momenta q y =0,πcorrespond to bonding and antibonding symmetry,respectively.Either one or both of the bands can be occupied in the noninteracting sys-tem,depending on the total particle density and the ratio of t ⊥and t .At quarter ﬁlling,the transition occurs at isotropic hopping:for t ⊥<t both bands are less than half–ﬁlled,whereas for t ⊥>t the bonding band is half–ﬁlled and the antibonding band is unoccupied.The eﬀect of the Hubbard interaction U on this sys-tem has been extensively studied.In the weak–coupling limit,U ≪t ,the phase diagram has been investigated using the perturbative renormalization group (RG).32A variety of phases have been shown to exist as a function of band ﬁlling and hopping anisotropy.In general,the two–band system can have four possible modes (symmet-ric and antisymmetric charge and spin modes),each of which can be either massive or massless.The phases can therefore be classiﬁed using the notation C n S m where n and m designate the number of gapless charge and spin modes,respectively (0≤n,m ≤2).At quarter ﬁlling,the weak–coupling RG 32for the “bare”Hubbard model (V =0)yields the following results:For t ⊥>t the system behaves as a half–ﬁlled Luttinger liquid;Umk-lapp scattering in the bonding channel is a relevant per-turbation which leads to a charge–gapped C0S1phase at small U .In contrast,deep in the two–band region,t ⊥≪t ,one ﬁnds a metallic C1S0phase in the weak–coupling limit.Near isotropic hopping,the bottom of the antibonding band just “touches”the Fermi surface,and the curvature of the dispersion becomes important,leading to additional narrow regions of C2S2and C2S1phases.Several of these weak–coupling predictions have been veriﬁed by numerical DMRG calculations in the in-termediate and strong coupling regimes for a wide range of ﬁlling.33Systematic studies of the phases of the ex-tended Hubbard model on a two–leg ladder away from half–ﬁlling have to our knowledge not yet been carried out.III.NUMERICAL RESULTSIn this section we present the results of our numeri-cal investigations and discuss the characteristics of the phases shown in Figs.1and 2.A.Technique and observablesThe numerical results have been calculated with the DMRG technique34on lattices of up to2×80sites with open boundary conditions at the ends of the chains as well as between the two chains.Most data shown are ob-tained by keeping600states per block,resulting in the sum of the discarded density matrix eigenvalues being typically10−8or less.For small system sizes we have checked the convergence by using up to1000states per block.Unless otherwise noted,we estimate the errors in the gap energies and correlation functions obtained using the DMRG procedure to be less than a few percent. Important ground–state properties are the static charge and spin correlation functions:we have calculated the static charge structure factor1C(q)=N av {j} δn j+iδn j ,(4)... denotes the ground–state expectation value,δn j= n j− n j ,and we average over typically N av=6sites to remove oscillations due to the open boundaries.The spin structure factor S(q)is deﬁned similarly in terms of the spin–spin correlation function S z j+i S z j .The nature of the low–lying excitations can be deter-mined by calculating the energy gaps of the system.In particular,we will consider the charge and spin gaps,de-ﬁned as1∆c=but the transition points shift to smaller t ⊥/t .A further increase of V suppresses the metallic phase,and only the spin gap transition remains.Data for V/t =2is shown in Fig.4:the behavior of the spin gap is similar to the V =0case,i.e.,it is ﬁnite for small t ⊥and vanishes for t ⊥/t larger than some critical value.However,the charge gap is found to be nonzero for all hopping ratios examined here (see also Figs.6and 7below).∆c / t ||t ⊥/t ||∆s / t ||FIG.4.Charge and spin gaps at U/t =8,V /t =0,2as function of the hopping ratio t ⊥/t .Since the ﬁnite–size eﬀects become substantial for small t ⊥,we have indicated the estimated errors from the extrapolation to the thermody-namic limit by error bars.For data points without error bars,the uncertainties are of the order of the symbol size or less.These data can be understood from the RG analysis of Ref.32:the additional nearest–neighbor repulsion does not introduce a new relevant operator,but only changes the scaling dimension of the perturbation introduced by U .This implies that small V does not modify the phases found at V =0.However,our data indicate that rela-tively small values of V are enough to drive the system to an insulating state even for t ⊥<t .C.CDW phases and charge ordering transitionAs the nearest–neighbor repulsion V is increased,we expect a transition to a checkerboard charge–ordered state.As this has been examined in our earlier paper,31here we summarize the main ﬁndings:At large V ,an in-sulating CDW state with ordering wavevector Q =(π,π)occurs for all ﬁllings between quarter and half–ﬁlling.At quarter–ﬁlling,the transition is second order,i.e.,the order parameter η=lim L →∞C (Q )/ n 2vanishes con-tinuously upon approaching a critical V c (U )from above.Interestingly,the transition has been found to change from second–order to ﬁrst–order at higher band ﬁlling as a function of U/t ;31such tricritical behavior has also been observed in the 1D case at half–ﬁlling.20,22In thequarter ﬁlled CDW state,the spin correlations indicate zigzag antiferromagnetic ordering of the spins 1ηindicating a second–order transi-tion at V c /t =3.45±0.1.We now turn to our new results and a more detailed discussion of the quarter–ﬁlled system.In Fig.5,the ﬁnite–size scaling for ηas well as the extrapolated values for√00.51√ηV / t ||024∆c / t||1234567800.010.020.030.04∆s / t ||t ⊥/t || = 0.7FIG.6.Order parameter√N 2[E 0(L,N +2)+E 0(L,N −2)−2E 0(L,N )]−1.(6)Our results clearly show the occurence of phase sepa-ration in the large V ,small U region indicated by (i)a diverging compressibility,(ii)oscillating incommensurate spin and charge correlations with wave vectors strongly dependent on the system size,and (iii)the occurence of site charge densities greater than unity.Note that at quarter ﬁlling no double occupancies occur even in the perfectly charge–ordered state.The appearance of doubly occupied sites in the phase–separated state is clearly consistent with the phase–separation mechanismexplained above.The criteria (i)–(iii)give consistent re-sults and allow for areasonably accurate determination of the PS boundary (see Fig.1),even though ﬁnite–size ef-fects in the calculation of the compressibility are large.19C (q )S (q )q x q xFIG.8.Charge and spin correlation functions for a 64×2system with isotropic hopping and U/t =2.The rapid oscil-lations in C (q )at V /t =8indicate that increasing V drives the system into phase separation.In contrast to that found in the 1D chain,the phase–separation boundary has non–monotonic behavior,i.e.U PS (V )shows a maximum at around V/t ≈8,U/t ≈2.4,as can be seen in Fig.1.The described “re–entrant”(non–monotonic)behavior of the PS boundary is illus-trated in Fig.9in which we display the charge gap as a function of V for U/t =2.2.Here we ﬁnd a homo-geneous phase at small V ,a charge–ordered phase at large V ,and a region of phase separation in between,for 4.8<V/t <13.5.Another diﬀerence with the behavior of the single–chain extended Hubbard model is that no homogeneous phase appears for large V and small or intermediate val-ues of U :increasing U in the PS region drives the system directly into the charge–ordered state (Fig.1).In con-trast,in the 1D system,a homogeneous phase is present at any V and the boundaries to the charge–ordered and to the PS phases merge (at U/t =4)only in the V →∞limit.19For the present ladder system,the behavior at the boundary between the charge–ordered state and the PS region is quite interesting:The charge gap appears to vanish continuously at this boundary (Fig.9).However,the charge–density wave order parameter√2,and thespin states are degenerate for V =∞.We would like to discuss the spin ordering arising from eﬀective exchange interactions which occur for small but ﬁnite t/V .We can do this by treating t/V as a perturbation,in a manner similar to the derivation of the eﬀective spin exchange in the large–U Hubbard model at half–ﬁlling which leads to the mapping to an antiferromagnetic Heisenberg model.However,the present problem is slightly more compli-cated because the degeneracy is lifted in fourth order in the hopping rather than in second order as in the half–ﬁlled Hubbard model.The aim is to ﬁnd an eﬀective Hamiltonian for the residual spin degrees of freedom.It is easy to see that this model will be a frustrated antiferromagnetic Heisen-berg J 1–J 2chain where J 1and J 2are a diagonal (1,1)and a horizontal (2,0)coupling between the spins in the checkerboard ordered state.It is well–known 37–40that this model has a zero–temperature phase transition as a function of α=J 2/J 1.For α<αc the ground state is gapless with power–law correlations.For α>αc a spon-taneous dimerization occurs which leads to a spin gapand a doubly degenerate ground state.The numerical estimate 38for αc is 0.2411.At α=1/2(the Majumdar–Ghosh point),the ground state has been shown to be an exact product of nearest–neighbor singlets.41Therefore,a corresponding spin–gap transition is also possible in the charge–ordered state of the t −U −V ladder (i.e.,a CDW –CDW sg transition)provided that the eﬀective αcan be tuned through the critical value by changing the system parameters.00.51 1.52 2.53 3.54V || / U0.10.20.30.40.5α = J 2 / J 1FIG.10.The ratio of the eﬀective coupling constants α=J 2/J 1calculated from Eq.(A2)at isotropic hopping.The diﬀerent curves correspond to V ⊥/V =0,0.5,1[thick line –see Eq.(7)]and 2from top to bottom.In order to ob-tain values for anisotropic hopping,αmust be multiplied by (t /t ⊥)2.The horizontal dashed line marks the critical value αc =0.2411for the dimerization transition of the frustrated spin chain.We use a recently developed method 42based on cu-mulants to derive an eﬀective Hamiltonian for the spin degrees of freedom in the charge–ordered state of the quarter–ﬁlled model.We give the derivation in the ap-pendix,and here state only the ﬁnal result for isotropic nearest–neighbor repulsion,V =V ⊥=V :J 1=2t 2⊥t 2U+2VJ 2=t 4U +2thecharge–ordered phase.Data for the frustrated spin chain from Ref.40are also shown for comparison.Note that the data are plotted as a function of the ratio J 2/J 1with the values of these eﬀective couplings taken from the strong–coupling expressions (7).The spin gap value follows the strong coupling prediction closely even for in-termediate values of U/t and V/t .The peak position also shows the expected behavior,i.e.,it deviates from πwhen the eﬀective J 2/J 1exceeds a certain value.For large U and V ,the agreement with the results from the frustrated spin chain is nearly perfect,clearly indicating that the spin dynamics in the strong–coupling charge–ordered state is correctly described by the J 1–J 2spin chain.For smaller values of U and V ,there are slight deviations in the peak position from the spin chain data:the region of incommensurate spin order becomes nar-rower with decreasing interaction.This might be ex-pected because there is no incommensurability at half–ﬁlling in the non–interacting limit.A similar behavior for S (q )has been found for the half–ﬁlled Hubbard chain with next–nearest–neighbor hopping 43which can also be mapped onto an eﬀective frustrated spin chain in the large–U limit.21∆s / J 121q * / πFIG.12.Spin gap (left)and peak position in the spinstructure factor (right)for the charge–ordered state of the quarter–ﬁlled t −U −V ladder.The diﬀerent curves are obtained by varying the hopping ratio t /t ⊥at ﬁxed values of U/t ⊥and V /t ⊥.The horizontal axis shows the ratio of the eﬀective exchange constants J 1and J 2obtained from the strong–coupling expressions (7).Data marked ”J 1–J 2chain”are taken from Ref.40.Now we turn to a discussion of the special case of isotropic hopping for which the V =0weak coupling sys-tem is near the one–band to two–band transition.The numerical results obtained by DMRG indicate a zero spin gap and nonzero charge gap for any ﬁnite V (outside the phase–separation region).This is in disagreement with the strong–coupling analysis presented above which predicts a CDW sg phase at large V/U due to sponta-neous dimerization.Since α=J 2/J 1is close to αc ,however,the spin gap would be very small and therefore hard to observe using numerical methods.By assum-ing that the strong–coupling picture is also valid in the intermediate–coupling regime,we can locate the CDW –CDW sg boundary as shown in Fig.1.Since it is not possible to deduce the behavior of the spin gap close to the charge–order transition from the current numer-ical results,we cannot decide whether the charge–order transition line and the spin–gap transition line meet for the case of isotropic hopping.Additional numerical ap-proaches (e.g.,based on level–crossing methods)could be used to check the spin–gap scenario and to determine the precise location of the boundary of the spin–gap phase.It is worth pointing out that although a spin gap is present in both the homogeneous and the charge–ordered phases at small t ⊥/t ,the mechanisms for the spin gap opening appear to be quite diﬀerent:The strong–coupling CDW –CDW sg transition involves spontaneous dimerization in a spin model and is described by a sine–Gordon theory,whereas the weak–coupling case at V =0is more complicated due to the presence of low–lying charge modes (see Ref.32for a discussion on the RG for V =0),however,not much is known about the V >0case.V.CONCLUSIONSIn summary,we have studied the phase diagram of the extended Hubbard model on a quarter–ﬁlled two–leg ladder.At very small V ,the system behaves as in the V =0case 32,while slightly larger values of V lead to an insulating state with either zero (HI)or nonzero (HI sg )spin gap depending on the hopping anisotropy.For U and V both strong,the ground state shows zigzag charge order.In this phase each occupied site carries spin 12chain in thestrong coupling limit,U,V ≫t .This eﬀective spin chain can be either in the gapless regime (CDW)with alge-braic spin correlations or in the spontaneously dimer-ized regime (CDW sg )with gapped spin excitations.For t ⊥<t ,the spin gap in the charge–ordered state could be numerically observed.Its magnitude is in good agree-ment with the results for a corresponding J 1–J 2spin chain down to U/t =4.The dimerization of the eﬀective spin chain can be interpreted as bond–order wave 44in the original Hubbard model,so the system has an insu-lating CDW sg ground state with coexisting bond–order and charge–density waves.Finally,at small values of U and moderate to large values of V ,the system phase sep-arates into a phase of immobile double occupancies on every second site and a phase of mobile single electrons.We have identiﬁed a purely electronic mechanism for the opening of a spin gap in a quarter–ﬁlled CDW sys-tem on a ladder based on the physics of a frustrated spin chain.However,we note here that the spin–gap。

单分子综述-NATURE NANOTECHNOLOGY-Single-molecule junctions beyond electronic transport-2013

Stimulated by the initial proposal that molecules could be used as the functional building blocks in electronic devices 1, researchers around the world have been probing transport phenomena at the single-molecule level both experimentally and theoretically 2–11. Recent experimental advances include the demonstration of conductance switching 12–16, rectification 17–21, and illustrations on how quantum interference effects 22–26 play a critical role in the electronic properties of single metal–molecule–metal junctions. The focus of these experiments has been to both provide a fundamental understanding of transport phenomena in nanoscale devices as well as to demonstrate the engineering of functionality from rational chemical design in single-molecule junctions. Although so far there are no ‘molecular electronics’ devices manufactured commercially, basic research in this area has advanced significantly. Specifically, the drive to create functional molecular devices has pushed the frontiers of both measurement capabilities and our fundamental understanding of varied physi-cal phenomena at the single-molecule level, including mechan-ics, thermoelectrics, optoelectronics and spintronics in addition to electronic transport characterizations. Metal–molecule–metal junctions thus represent a powerful template for understanding and controlling these physical and chemical properties at the atomic- and molecular-length scales. I n this realm, molecular devices have atomically defined precision that is beyond what is achievable at present with quantum dots. Combined with the vast toolkit afforded by rational molecular design 27, these techniques hold a significant promise towards the development of actual devices that can transduce a variety of physical stimuli, beyond their proposed utility as electronic elements 28.n this Review we discuss recent measurements of physi-cal properties of single metal–molecule–metal junctions that go beyond electronic transport characterizations (Fig. 1). We present insights into experimental investigations of single-molecule junc-tions under different stimuli: mechanical force, optical illumina-tion and thermal gradients. We then review recent progress in spin- and quantum interference-based phenomena in molecular devices. I n what follows, we discuss the emerging experimentalSingle-molecule junctions beyond electronic transportSriharsha V. Aradhya and Latha Venkataraman*The id ea of using ind ivid ual molecules as active electronic components provid ed the impetus to d evelop a variety of experimental platforms to probe their electronic transport properties. Among these, single-molecule junctions in a metal–molecule–metal motif have contributed significantly to our fundamental understanding of the principles required to realize molecular-scale electronic components from resistive wires to reversible switches. The success of these techniques and the growing interest of other disciplines in single-molecule-level characterization are prompting new approaches to investigate metal–molecule–metal junctions with multiple probes. Going beyond electronic transport characterization, these new studies are highlighting both the fundamental and applied aspects of mechanical, optical and thermoelectric properties at the atomic and molecular scales. Furthermore, experimental demonstrations of quantum interference and manipulation of electronic and nuclear spins in single-molecule circuits are heralding new device concepts with no classical analogues. In this Review, we present the emerging methods being used to interrogate multiple properties in single molecule-based devices, detail how these measurements have advanced our understanding of the structure–function relationships in molecular junctions, and discuss the potential for future research and applications.methods, focusing on the scientific significance of investigations enabled by these methods, and their potential for future scientific and technological progress. The details and comparisons of the dif-ferent experimental platforms used for electronic transport char-acterization of single-molecule junctions can be found in ref. 29. Together, these varied investigations underscore the importance of single-molecule junctions in current and future research aimed at understanding and controlling a variety of physical interactions at the atomic- and molecular-length scale.Structure–function correlations using mechanicsMeasurements of electronic properties of nanoscale and molecu-lar junctions do not, in general, provide direct structural informa-tion about the junction. Direct imaging with atomic resolution as demonstrated by Ohnishi et al.30 for monoatomic Au wires can be used to correlate structure with electronic properties, however this has not proved feasible for investigating metal–molecule–metal junctions in which carbon-based organic molecules are used. Simultaneous mechanical and electronic measurements provide an alternate method to address questions relating to the struc-ture of atomic-size junctions 31. Specifically, the measurements of forces across single metal–molecule–metal junctions and of metal point contacts provide independent mechanical information, which can be used to: (1) relate junction structure to conduct-ance, (2) quantify bonding at the molecular scale, and (3) provide a mechanical ‘knob’ that can be used to control transport through nanoscale devices. The first simultaneous measurements of force and conductance in nanoscale junctions were carried out for Au point contacts by Rubio et al.32, where it was shown that the force data was unambiguously correlated to the quantized changes in conductance. Using a conducting atomic force microscope (AFM) set-up, Tao and coworkers 33 demonstrated simultaneous force and conductance measurements on Au metal–molecule–metal junc-tions; these experiments were performed at room temperature in a solution of molecules, analogous to the scanning tunnelling microscope (STM)-based break-junction scheme 8 that has now been widely adopted to perform conductance measurements.Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA. *e-mail: lv2117@DOI: 10.1038/NNANO.2013.91These initial experiments relied on the so-called static mode of AFM-based force spectroscopy, where the force on the canti-lever is monitored as a function of junction elongation. I n this method the deflection of the AFM cantilever is directly related to the force on the junction by Hooke’s law (force = cantilever stiff-ness × cantilever deflection). Concurrently, advances in dynamic force spectroscopy — particularly the introduction of the ‘q-Plus’ configuration 34 that utilizes a very stiff tuning fork as a force sen-sor — are enabling high-resolution measurements of atomic-size junctions. In this technique, the frequency shift of an AFM cantilever under forced near-resonance oscillation is measuredas a function of junction elongation. This frequency shift can be related to the gradient of the tip–sample force. The underlying advantage of this approach is that frequency-domain measure-ments of high-Q resonators is significantly easier to carry out with high precision. However, in contrast to the static mode, recover-ing the junction force from frequency shifts — especially in the presence of dissipation and dynamic structural changes during junction elongation experiments — is non-trivial and a detailed understanding remains to be developed 35.The most basic information that can be determined throughsimultaneous measurement of force and conductance in metalThermoelectricsSpintronics andMechanicsOptoelectronicsHotColdFigure 1 | Probing multiple properties of single-molecule junctions. phenomena in addition to demonstrations of quantum mechanical spin- and interference-dependent transport concepts for which there are no analogues in conventional electronics.contacts is the relation between the measured current and force. An experimental study by Ternes et al.36 attempted to resolve a long-standing theoretical prediction 37 that indicated that both the tunnelling current and force between two atomic-scale metal contacts scale similarly with distance (recently revisited by Jelinek et al.38). Using the dynamic force microscopy technique, Ternes et al. effectively probed the interplay between short-range forces and conductance under ultrahigh-vacuum conditions at liquid helium temperatures. As illustrated in Fig. 2a, the tunnel-ling current through the gap between the metallic AFM probe and the substrate, and the force on the cantilever were recorded, and both were found to decay exponentially with increasing distance with nearly the same decay constant. Although an exponential decay in current with distance is easily explained by considering an orbital overlap of the tip and sample wavefunctions through a tunnel barrier using Simmons’ model 39, the exponential decay in the short-range forces indicated that perhaps the same orbital controlled the interatomic short-range forces (Fig. 2b).Using such dynamic force microscopy techniques, research-ers have also studied, under ultrahigh-vacuum conditions, forces and conductance across junctions with diatomic adsorbates such as CO (refs 40,41) and more recently with fullerenes 42, address-ing the interplay between electronic transport, binding ener-getics and structural evolution. I n one such experiment, Tautz and coworkers 43 have demonstrated simultaneous conduct-ance and stiffness measurements during the lifting of a PTCDA (3,4,9,10-perylene-tetracarboxylicacid-dianhydride) molecule from a Ag(111) substrate using the dynamic mode method with an Ag-covered tungsten AFM tip. The authors were able to follow the lifting process (Fig. 2c,d) monitoring the junction stiffness as the molecule was peeled off the surface to yield a vertically bound molecule, which could also be characterized electronically to determine the conductance through the vertical metal–molecule–metal junction with an idealized geometry. These measurements were supported by force field-based model calculations (Fig. 2c and dashed black line in Fig. 2d), presenting a way to correlate local geometry to the electronic transport.Extending the work from metal point contacts, ambient meas-urements of force and conductance across single-molecule junc-tions have been carried out using the static AFM mode 33. These measurements allow correlation of the bond rupture forces with the chemistry of the linker group and molecular backbone. Single-molecule junctions are formed between a Au-metal sub-strate and a Au-coated cantilever in an environment of molecules. Measurements of current through the junction under an applied bias determine conductance, while simultaneous measurements of cantilever deflection relate to the force applied across the junction as shown in Fig. 2e. Although measurements of current throughzF zyxCantileverIVabConductance G (G 0)1 2 3Tip–sample distance d (Å)S h o r t -r a n g e f o r c e F z (n N )10−310−210−11110−110−210−3e10−410−210C o n d u c t a n c e (G 0)Displacement86420Force (nN)0.5 nm420−2F o r c e (n N )−0.4−0.200.20.4Displacement (nm)SSfIncreasing rupture forcegc(iv)(i)(iii)(ii)Low HighCounts d9630−3d F /d z (n N n m −1)(i)(iv)(iii)(ii)A p p r o a chL i ft i n g110−210−4G (2e 2/h )2051510z (Å)H 2NNH 2H 2NNH 2NNFigure 2 | Simultaneous measurements of electronic transport and mechanics. a , A conducting AFM set-up with a stiff probe (shown schematically) enabled the atomic-resolution imaging of a Pt adsorbate on a Pt(111) surface (tan colour topography), before the simultaneous measurement of interatomic forces and currents. F z , short-range force. b , Semilogarithmic plot of tunnelling conductance and F z measured over the Pt atom. A similar decay constant for current and force as a function of interatomic distance is seen. The blue dashed lines are exponential fits to the data. c , Structural snapshots showing a molecular mechanics simulation of a PTCDA molecule held between a Ag substrate and tip (read right to left). It shows the evolution of the Ag–PTCDA–Ag molecular junction as a function of tip–surface distance. d , Upper panel shows experimental stiffness (d F /d z ) measurements during the lifting process performed with a conducting AFM. The calculated values from the simulation are overlaid (dashed black line). Lower panel shows simultaneously measured conductance (G ). e , Simultaneously measured conductance (red) and force (blue) measurements showing evolution of a molecular junction as a function of junction elongation. A Au point contact is first formed, followed by the formation of a single-molecule junction, which then ruptures on further elongation. f , A two-dimensional histogram of thousands of single-molecule junctionrupture events (for 1,4-bis(methyl sulphide) butane; inset), constructed by redefining the rupture location as the zero displacement point. The most frequently measured rupture force is the drop in force (shown by the double-headed arrow) at the rupture location in the statistically averaged force trace (overlaid black curve). g , Beyond the expected dependence on the terminal group, the rupture force is also sensitive to the molecular backbone, highlighting the interplay between chemical structure and mechanics. In the case of nitrogen-terminated molecules, rupture force increases fromaromatic amines to aliphatic amines and the highest rupture force is for molecules with pyridyl moieties. Figure reproduced with permission from: a ,b , ref. 36, © 2011 APS; c ,d , ref. 43, © 2011 APS.DOI: 10.1038/NNANO.2013.91such junctions are easily accomplished using standard instru-mentation, measurements of forces with high resolution are not straightforward. This is because a rather stiff cantilever (with a typical spring constant of ~50 N m−1) is typically required to break the Au point contact that is first formed between the tip and sub-strate, before the molecular junctions are created. The force reso-lution is then limited by the smallest deflection of the cantilever that can be measured. With a custom-designed system24 our group has achieved a cantilever displacement resolution of ~2 pm (com-pare with Au atomic diameter of ~280 pm) using an optical detec-tion scheme, allowing the force noise floor of the AFM set-up to be as low as 0.1 nN even with these stiff cantilevers (Fig. 2e). With this system, and a novel analysis technique using two-dimensional force–displacement histograms as illustrated in Fig. 2f, we have been able to systematically probe the influence of the chemical linker group44,45 and the molecular backbone46 on single-molecule junction rupture force as illustrated in Fig. 2g.Significant future opportunities with force measurements exist for investigations that go beyond characterizations of the junc-tion rupture force. In two independent reports, one by our group47 and another by Wagner et al.48, force measurements were used to quantitatively measure the contribution of van der Waals interac-tions at the single-molecule level. Wagner et al. used the stiffness data from the lifting of PTCDA molecules on a Au(111) surface, and fitted it to the stiffness calculated from model potentials to estimate the contribution of the various interactions between the molecule and the surface48. By measuring force and conductance across single 4,4’-bipyridine molecules attached to Au electrodes, we were able to directly quantify the contribution of van der Waals interactions to single-molecule-junction stiffness and rupture force47. These experimental measurements can help benchmark the several theoretical frameworks currently under development aiming to reliably capture van der Waals interactions at metal/ organic interfaces due to their importance in diverse areas includ-ing catalysis, electronic devices and self-assembly.In most of the experiments mentioned thus far, the measured forces were typically used as a secondary probe of junction prop-erties, instead relying on the junction conductance as the primary signature for the formation of the junction. However, as is the case in large biological molecules49, forces measured across single-mol-ecule junctions can also provide the primary signature, thereby making it possible to characterize non-conducting molecules that nonetheless do form junctions. Furthermore, molecules pos-sess many internal degrees of motion (including vibrations and rotations) that can directly influence the electronic transport50, and the measurement of forces with such molecules can open up new avenues for mechanochemistry51. This potential of using force measurements to elucidate the fundamentals of electronic transport and binding interactions at the single-molecule level is prompting new activity in this area of research52–54. Optoelectronics and optical spectroscopyAddressing optical properties and understanding their influence on electronic transport in individual molecular-scale devices, col-lectively referred to as ‘molecular optoelectronics’, is an area with potentially important applications55. However, the fundamental mismatch between the optical (typically, approximately at the micrometre scale) and molecular-length scales has historically presented a barrier to experimental investigations. The motiva-tions for single-molecule optoelectronic studies are twofold: first, optical spectroscopies (especially Raman spectroscopy) could lead to a significantly better characterization of the local junction structure. The nanostructured metallic electrodes used to real-ize single-molecule junctions are coincidentally some of the best candidates for local field enhancement due to plasmons (coupled excitations of surface electrons and incident photons). This there-fore provides an excellent opportunity for understanding the interaction of plasmons with molecules at the nanoscale. Second, controlling the electronic transport properties using light as an external stimulus has long been sought as an attractive alternative to a molecular-scale field-effect transistor.Two independent groups have recently demonstrated simulta-neous optical and electrical measurements on molecular junctions with the aim of providing structural information using an optical probe. First, Ward et al.56 used Au nanogaps formed by electromi-gration57 to create molecular junctions with a few molecules. They then irradiated these junctions with a laser operating at a wavelength that is close to the plasmon resonance of these Au nanogaps to observe a Raman signal attributable to the molecules58 (Fig. 3a). As shown in Fig. 3b, they observed correlations between the intensity of the Raman features and magnitude of the junction conductance, providing direct evidence that Raman signatures could be used to identify junction structures. They later extended this experimental approach to estimate vibrational and electronic heating in molecu-lar junctions59. For this work, they measured the ratio of the Raman Stokes and anti-Stokes intensities, which were then related to the junction temperature as a function of the applied bias voltage. They found that the anti-Stokes intensity changed with bias voltage while the Stokes intensity remained constant, indicating that the effective temperature of the Raman-active mode was affected by passing cur-rent through the junction60. Interestingly, Ward et al. found that the vibrational mode temperatures exceeded several hundred kelvin, whereas earlier work by Tao and co-workers, who used models for junction rupture derived from biomolecule research, had indicated a much smaller value (~10 K) for electronic heating61. Whether this high temperature determined from the ratio of the anti-Stokes to Stokes intensities indicates that the electronic temperature is also similarly elevated is still being debated55, however, one can definitely conclude that such measurements under a high bias (few hundred millivolts) are clearly in a non-equilibrium transport regime, and much more research needs to be performed to understand the details of electronic heating.Concurrently, Liu et al.62 used the STM-based break-junction technique8 and combined this with Raman spectroscopy to per-form simultaneous conductance and Raman measurements on single-molecule junctions formed between a Au STM tip and a Au(111) substrate. They coupled a laser to a molecular junction as shown in Fig. 3c with a 4,4’-bipyridine molecule bridging the STM tip (top) and the substrate (bottom). Pyridines show clear surface-enhanced Raman signatures on metal58, and 4,4’-bipy-ridine is known to form single-molecule junctions in the STM break-junction set-up8,15. Similar to the study of Ward et al.56, Liu et al.62 found that conducting molecular junctions had a Raman signature that was distinct from the broken molecu-lar junctions. Furthermore, the authors studied the spectra of 4,4’-bipyridine at different bias voltages, ranging from 10 to 800 mV, and reported a reversible splitting of the 1,609 cm–1 peak (Fig. 3d). Because this Raman signature is due to a ring-stretching mode, they interpreted this splitting as arising from the break-ing of the degeneracy between the rings connected to the source and drain electrodes at high biases (Fig. 3c). Innovative experi-ments such as these have demonstrated that there is new physics to be learned through optical probing of molecular junctions, and are initiating further interest in understanding the effect of local structure and vibrational effects on electronic transport63. Experiments that probe electroluminescence — photon emis-sion induced by a tunnelling current — in these types of molec-ular junction can also offer insight into structure–conductance correlations. Ho and co-workers have demonstrated simultaneous measurement of differential conductance and photon emissionDOI: 10.1038/NNANO.2013.91from individual molecules at a submolecular-length scale using an STM 64,65. Instead of depositing molecules directly on a metal sur-face, they used an insulating layer to decouple the molecule from the metal 64,65 (Fig. 3e). This critical factor, combined with the vac-uum gap with the STM tip, ensures that the metal electrodes do not quench the radiated photons, and therefore the emitted photons carry molecular fingerprints. Indeed, the experimental observation of molecular electroluminescence of C 60 monolayers on Au(110) by Berndt et al.66 was later attributed to plasmon-mediated emission of the metallic electrodes, indirectly modulated by the molecule 67. The challenge of finding the correct insulator–molecule combination and performing the experiments at low temperature makes electro-luminescence relatively uncommon compared with the numerous Raman studies; however, progress is being made on both theoretical and experimental fronts to understand and exploit emission pro-cesses in single-molecule junctions 68.Beyond measurements of the Raman spectra of molecular junctions, light could be used to control transport in junctions formed with photochromic molecular backbones that occur in two (or more) stable and optically accessible states. Some common examples include azobenzene derivatives, which occur in a cis or trans form, as well as diarylene compounds that can be switched between a conducting conjugated form and a non-conducting cross-conjugated form 69. Experiments probing the conductance changes in molecular devices formed with such compounds have been reviewed in depth elsewhere 70,71. However, in the single-mol-ecule context, there are relatively few examples of optical modula-tion of conductance. To a large extent, this is due to the fact that although many molecular systems are known to switch reliably in solution, contact to metallic electrodes can dramatically alter switching properties, presenting a significant challenge to experi-ments at the single-molecule level.Two recent experiments have attempted to overcome this chal-lenge and have probed conductance changes in single-molecule junctions while simultaneously illuminating the junctions with visible light 72,73. Battacharyya et al.72 used a porphyrin-C 60 ‘dyad’ molecule deposited on an indium tin oxide (I TO) substrate to demonstrate the light-induced creation of an excited-state mol-ecule with a different conductance. The unconventional transpar-ent ITO electrode was chosen to provide optical access while also acting as a conducting electrode. The porphyrin segment of the molecule was the chromophore, whereas the C 60 segment served as the electron acceptor. The authors found, surprisingly, that the charge-separated molecule had a much longer lifetime on ITO than in solution. I n the break-junction experiments, the illuminated junctions showed a conductance feature that was absent without1 μm Raman shift (cm –1)1,609 cm –1(–)Source 1,609 cm–1Drain (+)Low voltage High voltageMgPNiAl(110)STM tip (Ag)VacuumThin alumina 1.4 1.5 1.6 1.701020 3040200400Photon energy (eV)3.00 V 2.90 V 2.80 V 2.70 V 2.60 V2.55 V 2.50 VP h o t o n c o u n t s (a .u .)888 829 777731Wavelength (nm)Oxideacebd f Raman intensity (CCD counts)1,5001,00050000.40.30.20.10.01,590 cm −11,498 cm −1d I /d V (μA V –1)1,609 cm –11,631 cm–11 μm1 μmTime (s)Figure 3 | Simultaneous studies of optical effects and transport. a , A scanning electron micrograph (left) of an electromigrated Au junction (light contrast) lithographically defined on a Si substrate (darker contrast). The nanoscale gap results in a ‘hot spot’ where Raman signals are enhanced, as seen in the optical image (right). b , Simultaneously measured differential conductance (black, bottom) and amplitudes of two molecular Raman features (blue traces, middle and top) as a function of time in a p-mercaptoaniline junction. c , Schematic representation of a bipyridine junction formed between a Au STM tip and a Au(111) substrate, where the tip enhancement from the atomically sharp STM tip results in a large enhancement of the Raman signal. d , The measured Raman spectra as a function of applied bias indicate breaking of symmetry in the bound molecule. e , Schematic representation of a Mg-porphyrin (MgP) molecule sandwiched between a Ag STM tip and a NiAl(110) substrate. A subnanometre alumina insulating layer is a key factor in measuring the molecular electroluminescence, which would otherwise be overshadowed by the metallic substrate. f , Emission spectra of a single Mg-porphyrin molecule as a function of bias voltage (data is vertically offset for clarity). At high biases, individual vibronic peaks become apparent. The spectra from a bare oxide layer (grey) is shown for reference. Figure reproduced with permission from: a ,b , ref. 56, © 2008 ACS; c ,d , ref. 62, © 2011 NPG; e ,f , ref. 65, © 2008 APS.DOI: 10.1038/NNANO.2013.91light, which the authors assigned to the charge-separated state. In another approach, Lara-Avila et al.73 have reported investigations of a dihydroazulene (DHA)/vinylheptafulvene (VHF) molecule switch, utilizing nanofabricated gaps to perform measurements of Au–DHA–Au single-molecule junctions. Based on the early work by Daub et al.74, DHA was known to switch to VHF under illumina-tion by 353-nm light and switch back to DHA thermally. In three of four devices, the authors observed a conductance increase after irradiating for a period of 10–20 min. In one of those three devices, they also reported reversible switching after a few hours. Although much more detailed studies are needed to establish the reliability of optical single-molecule switches, these experiments provide new platforms to perform in situ investigations of single-molecule con-ductance under illumination.We conclude this section by briefly pointing to the rapid pro-gress occurring in the development of optical probes at the single-molecule scale, which is also motivated by the tremendous interest in plasmonics and nano-optics. As mentioned previously, light can be coupled into nanoscale gaps, overcoming experimental chal-lenges such as local heating. Banerjee et al.75 have exploited these concepts to demonstrate plasmon-induced electrical conduction in a network of Au nanoparticles that form metal–molecule–metal junctions between them (Fig. 3f). Although not a single-molecule measurement, the control of molecular conductance through plas-monic coupling can benefit tremendously from the diverse set of new concepts under development in this area, such as nanofabri-cated transmission lines 76, adiabatic focusing of surface plasmons, electrical excitation of surface plasmons and nanoparticle optical antennas. The convergence of plasmonics and electronics at the fundamental atomic- and molecular-length scales can be expected to provide significant opportunities for new studies of light–mat-ter interaction 77–79.Thermoelectric characterization of single-molecule junctions Understanding the electronic response to heating in a single-mole-cule junction is not only of basic scientific interest; it can have a tech-nological impact by improving our ability to convert wasted heat into usable electricity through the thermoelectric effect, where a temper-ature difference between two sides of a device induces a voltage drop across it. The efficiency of such a device depends on its thermopower (S ; also known as the Seebeck coefficient), its electric and thermal conductivity 80. Strategies for increasing the efficiency of thermoelec-tric devices turned to nanoscale devices a decade ago 81, where one could, in principle, increase the electronic conductivity and ther-mopower while independently minimizing the thermal conductiv-ity 82. This has motivated the need for a fundamental understandingof thermoelectrics at the single-molecule level 83, and in particular, the measurement of the Seebeck coefficient in such junctions. The Seebeck coefficient, S = −(ΔV /ΔT )|I = 0, determines the magnitude of the voltage developed across the junction when a temperature dif-ference ΔT is applied, as illustrated in Fig. 4a; this definition holds both for bulk devices and for single-molecule junctions. If an addi-tional external voltage ΔV exists across the junction, then the cur-rent I through the junction is given by I = G ΔV + GS ΔT where G is the junction conductance 83. Transport through molecular junctions is typically in the coherent regime where conductance, which is pro-portional to the electronic transmission probability, is given by the Landauer formula 84. The Seebeck coefficient at zero applied voltage is then related to the derivative of the transmission probability at the metal Fermi energy (in the off-resonance limit), with, S = −∂E ∂ln( (E ))π2k 2B T E 3ewhere k B is the Boltzmann constant, e is the charge of the electron, T (E ) is the energy-dependent transmission function and E F is the Fermi energy. When the transmission function for the junction takes on a simple Lorentzian form 85, and transport is in the off-resonance limit, the sign of S can be used to deduce the nature of charge carriers in molecular junctions. In such cases, a positive S results from hole transport through the highest occupied molecu-lar orbital (HOMO) whereas a negative S indicates electron trans-port through the lowest unoccupied molecular orbital (LUMO). Much work has been performed on investigating the low-bias con-ductance of molecular junctions using a variety of chemical linker groups 86–89, which, in principle, can change the nature of charge carriers through the junction. Molecular junction thermopower measurements can thus be used to determine the nature of charge carriers, correlating the backbone and linker chemistry with elec-tronic aspects of conduction.Experimental measurements of S and conductance were first reported by Ludoph and Ruitenbeek 90 in Au point contacts at liquid helium temperatures. This work provided a method to carry out thermoelectric measurements on molecular junctions. Reddy et al.91 implemented a similar technique in the STM geome-try to measure S of molecular junctions, although due to electronic limitations, they could not simultaneously measure conductance. They used thiol-terminated oligophenyls with 1-3-benzene units and found a positive S that increased with increasing molecular length (Fig. 4b). These pioneering experiments allowed the iden-tification of hole transport through thiol-terminated molecular junctions, while also introducing a method to quantify S from statistically significant datasets. Following this work, our group measured the thermoelectric current through a molecular junction held under zero external bias voltage to determine S and the con-ductance through the same junction at a finite bias to determine G (ref. 92). Our measurements showed that amine-terminated mol-ecules conduct through the HOMO whereas pyridine-terminatedmolecules conduct through the LUMO (Fig. 4b) in good agree-ment with calculations.S has now been measured on a variety of molecular junctionsdemonstrating both hole and electron transport 91–95. Although the magnitude of S measured for molecular junctions is small, the fact that it can be tuned by changing the molecule makes these experiments interesting from a scientific perspective. Future work on the measurements of the thermal conductance at the molecu-lar level can be expected to establish a relation between chemical structure and the figure of merit, which defines the thermoelec-tric efficiencies of such devices and determines their viability for practical applications.SpintronicsWhereas most of the explorations of metal–molecule–metal junc-tions have been motivated by the quest for the ultimate minia-turization of electronic components, the quantum-mechanical aspects that are inherent to single-molecule junctions are inspir-ing entirely new device concepts with no classical analogues. In this section, we review recent experiments that demonstrate the capability of controlling spin (both electronic and nuclear) in single-molecule devices 96. The early experiments by the groups of McEuen and Ralph 97, and Park 98 in 2002 explored spin-depend-ent transport and the Kondo effect in single-molecule devices, and this topic has recently been reviewed in detail by Scott and Natelson 99. Here, we focus on new types of experiment that are attempting to control the spin state of a molecule or of the elec-trons flowing through the molecular junction. These studies aremotivated by the appeal of miniaturization and coherent trans-port afforded by molecular electronics, combined with the great potential of spintronics to create devices for data storage and quan-tum computation 100. The experimental platforms for conducting DOI: 10.1038/NNANO.2013.91。

perovskite

arXiv:1504] 28 Apr 2015
Aur´ elien M. A. Leguy and Piers R. F. Barnes
Department of Physics, Imperial College London, SW7 2AZ, UK (Dated: 29 April 2015)
Lattice dynamics and vibrational spectra of the orthorhombic, tetragonal and cubic phases of methylammonium lead iodide
Federico Brivio, Jarvist M. Frost, Jonathan M. Skelton, Adam J. Jackson, Oliver J. Weber, Mark T. Weller, and Aron Walsha)
a) Electronic
mail: a.walsh@
2 cells. Structure Models. The normal modes of a system are deﬁned for an equilibrium conﬁguration. Calculating the vibrations for a non-equilibrium structure will result in imaginary frequencies upon diagonalising the dynamical matrix. Therefore we have generated extremely well optimised structures of MAPbI3 . One challenge in calculating the phonons of hybrid perovskites is the soft nature and complicated potential energy landscape of some of the restoring potentials, particularly those involving the organic cation. Orthorhombic Phase. The orthorhombic perovskite structure is the low temperature ground state of MAPbI3 and maintains its stability up to ca. 165 K.19,22,23 A comparison of the enthalpy from DFT calculations conﬁrms this ordering in stability. The diﬀerence in enthalpy is small, just 2 meV per MAPbI3 unit compared to the most stable tetragonal phase, yet 90 meV compared to the high-temperature cubic phase. Initial diﬀraction pattern solutions assigned the P na21 space group.16,22 Recent analysis of higher quality powder neutron diﬀraction data reassigns √ it to P √nma (a D2h point group).19 The structure is a 2a × 2a × 2a supercell expansion of the simple cubic perovskite lattice, i.e. following the lattice transformation matrix 1 −1 0 1 1 0 . (1) 0 0 2 In the P na21 phase, the PbI6 octahedra are distorted and tilt as a+ b− b− in Glazer notation1 with respect to the orientation of the conventional cubic cell. In this low-temperature phase, the four molecular cations in the unit cell are static on the diagonals of the ab planes pointing towards the undistorted facets of the cuboctahedral cavity. Correspondingly, molecules belonging to diﬀerent planes are anti-aligned with a head-tail motif. Such an antiferroelectric alignment is expected from consideration of the molecular dipole-dipole interaction.24 In the low temperature orthorhombic phase the CH3 NH+ 3 sublattice is fully ordered (a low entropy state). The ordering may be sensitive to the material preparation and / or cooling rate into this phase, i.e. the degree of quasi-thermal equilibrium. It is possible that diﬀerent ordering might be frozen into the low temperature phase by epitaxy or application of external force or electric ﬁelds. Tetragonal Phase. At 165 K MAPbI3 goes through a ﬁrst-order phase transition to the tetragonal space group I 4/mcm (D4h point group), which continuously undergoes a second-order phase transition to the cubic phase by ca. 327 K19,22,23 . As √ with the √ orthorhombic phase, this can be considered a 2a × 2a × 2a expansion of the cubic perovskite unit cell. The molecular cations are no longer in ﬁxed position as in the orthorhombic phase. The molecules are disordered between two non-equivalent positions in each cage.23,25 .

凝聚态物理实验第三章第三节

• There should be other configuration with lower energy
a -
-
one electron per ion site
energy
-π/a
π/a
• standing waves at k = π/a (Bragg diffraction)
• energy is lowered for valence band electrons.
Peierls’ Theorem (1955)
Peierls' Theorem states that:
“a one-dimensional equally spaced chain with one electron per ion is unstable”.
a
a one-dimensional equally spaced chain
• Now the gap opens there, so the electronic energy is lowered!
• There is a fundamental change of the electronic property, what?
MIT due to Peierls transition
Sir Rudolf Ernst Peierls (1907 – 1995)
• He was the first to use the concept of "holes".
• He established "zones" before Brillouin and applied it to phonons.
• He discovered the Boltzmann equations for phonons and the Umklapp process.

Superfluid Friction and Late-time Thermal Evolution of Neutron Stars

Bennett Link1 blink@ Montana State University, Department of Physics, Bozeman MT 59717 ABSTRACT The recent temperature measurements of the two older isolated neutron stars PSR 1929+10 and PSR 0950+08 (ages of 3 × 106 and 2 × 107 yr, respectively) indicate that these objects are heated. A promising candidate heat source is friction between the neutron star crust and the superﬂuid it is thought to contain. We study the eﬀects of superﬂuid friction on the long-term thermal and rotational evolution of a neutron star. Diﬀerential rotation velocities between the superﬂuid and the crust (averaged over the inner crust moment of inertia) of ω ¯ ∼ 0.6 rad s−1 for PSR 1929+10 and ∼ 0.02 rad s−1 for PSR 0950+08 would account for their observed temperatures. These diﬀerential velocities could be sustained by pinning of superﬂuid vortices to the inner crust lattice with strengths of ∼ 1 MeV per nucleus. Pinned vortices can creep outward through thermal ﬂuctuations or quantum tunneling. For thermally-activated creep, the coupling between the superﬂuid and crust is highly sensitive to temperature. If pinning maintains large diﬀerential rotation (∼ 10 rad s−1 ), a feedback instability could occur in stars younger than ∼ 105 yr causing oscillations of the temperature and spin-down rate over a period of ∼ 0.3tage . For stars older than ∼ 106 yr, however, vortex creep occurs through quantum tunneling, and the creep velocity is too insensitive to temperature for a thermal-rotational instability to occur. These older stars could be heated through a steady process of superﬂuid friction. Subject headings: stars: interiors — stars: neutron — stars: evolution — stars: stability — superﬂuid — dense matter

Semileptonic decays of $D$ mesons in unquenched lattice QCD

a r Xi v :h e p -l a t /0309107v 1 16 S e p 20031Semileptonic decays of D mesons in unquenched lattice QCD ∗Masataka Okamoto a ,Massimo di Pierro b ,Aida X.El-Khadra c ,Steven Gottlieb d ,Andreas S.Kronfeld a ,Paul B.Mackenzie a ,Damian P.Menscher c ,Mehmet B.Oktay c ,and James N.Simone aa Fermi National Accelerator Laboratory,P.O.Box 500,Batavia,IL 60510bSchool of Computer Science,Telecommunications and Information Systems,DePaul University,Chicago,Illinois 60604cDepartment of Physics,University of Illinois,Urbana,IL 61801dDepartment of Physics,Indiana University,Bloomington,IN 47405We present our preliminary results for semileptonic form factors of D mesons in unquenched lattice QCD.Simulations are carried out with n f =2+1dynamical quarks using gauge conﬁgurations generated by the MILC collaboration.For the valence quarks,we adopt an improved staggered light quark action and the clover heavy quark action.Our results for D →K and D →πform factors at q 2=0are in agreement with the experimental values.1.INTRODUCTIONIn order to extract the CKM matrix element |V ub |accurately with experimental measurement of the semileptonic decay width,a precision lat-tice QCD calculation of the B →πform fac-tor is required.To check the reliability of lattice calculations of the heavy to light form factors,study of the semileptonic decays of D mesons,such as D →K and D →π,is a good test ground because the corresponding CKM matrices |V cs |and |V cd |are known more accurately than |V ub |.Furthermore,forthcoming experiments by the CLEO-c collaboration will provide more strin-gent checks of lattice calculations in the D meson system.We have started new lattice calculations of heavy quark physics in unquenched QCD[1],and here we report our preliminary results for semilep-tonic form factors of D mesons.We are us-ing unquenched gauge conﬁgurations with n f =2+1improved staggered quarks generated by the MILC collaboration[2],with which the systematic errors due to the quenched approximation should be almost absent.For the valence light quarks,we adopt an improved staggered quark action,C π2(t y ,p π)CD 2(t x −t y ,p D )(2)with the D meson (Wilson-Naive)2-point func-tion C D2and the pion (Naive-Naive)2-point func-tion C π2.Care is needed,however,for the overall2Table1Quark mass,statistics and the sink time. m sea l/m sea s m val l/m val s conf t xq2q µ+f0(q2)m2D−m2π2m D vµf (E)+pµ⊥f⊥(E) with q=p D−pπ,v=p D/m D,p⊥=pπ−Ev and E=Eπ.The second expression using f and f⊥is more convenient when one considers the heavy quark expansion and the chiral limit.4.1.D s→ηsIn Fig.1we summarize the results of formfactors f0and f+for the D s→ηs(s¯s)decay3(aE)20.511.52m l0.20.40.60.811.21.4Figure 2.Chiral extrapolation for f D →π⊥.120.511.5f 0f +experimentD−>π12q 2 [GeV 2]0.511.5f 0f +experimentD−>KFigure 3.D →πand D →K form factors.obtained with the naive(staggered)light quarks and previous results[5]with the Wilson-type light quarks.The lines in the ﬁgure are ﬁtting curves with a parametrization by Becirevic and Kaidalov (BK)[6].One can see a nice agreement be-tween the quenched result with the naive quarks (squares,dashed line)and that with the Wilson-type quarks (circles,dotted),showing that our new method works well.We also note that the un-quenched result (diamonds,solid)is larger than quenched ones for q 2>0.See also Ref.[7]for a similar comparison for the B s →ηs form factors.4.2.D →πand D →KTo obtain D →π/K form factors at the phys-ical quark mass,we need to perform a chiral ex-trapolation using data in range of m val l=0.01-0.03.We do this for f and f ⊥at ﬁxed pion(kaon)energies E π(K )because the chiral perturbationformulas for the heavy to light form factors aregiven in such a way[8].In order to interpolate and extrapolate the results to common values of E π,we use a ﬁt with the BK parametrization.We then perform a linear chiral extrapolation in m val l at nine values of (aE π)2.One example of theseprocedures is shown in Fig.2for f D →π⊥.Finally f and f ⊥are converted to f 0and f +.The D →πand D →K form factors are shown in Fig.3together with experimental values at q 2=0[9].Our results at q 2=0aref D →K +(0)=0.75(3),f D →π+(0)=0.64(3)(3)with statistical errors only,whereas experimentalvalues are f D →K +(0)=0.73(2)and f D →π+(0)=0.73(13)with |V cs |=0.996(13)and |V cd |=0.224(16)[9].Our results are in agreement with the experimental values.The analysis including the chiral logarithm and the one-loop renormal-ization constant is underway.Acknowledgments:We thank the MILC collab-oration for the use of their conﬁgurations,and the Fermilab Computing Division and the SciDAC program for their support.Fermilab is operated by Universities Research Association Inc.,under contract with the DOE.REFERENCES1.See also,P.Mackenzie and J.Simone,theseproceedings.2. C.Bernard et al.(MILC collaboration),Phys.Rev.D 64,054506(2001).3.M.Wingate et al.Phys.Rev.D 67,054505(2003)4. A.X.El-Khadra,A.Kronfeld and P.Macken-zie,Phys.Rev.D 55,3933(1997).5. A.X.El-Khadra et al.Phys.Rev.D 64,014502(2001)6. D.Becirevic and A.B.Kaidalov,Phys.Lett.B 478,417(2000)7. C.DeTar,these proceedings.8. D.Becirevic,S.Prelovsek and J.Zupan,Phys.Rev.D 67,054010(2003)9.K.Hagiwara et al.[Particle Data Group Col-laboration],Phys.Rev.D 66,010001(2002);C.Caso et al.Eur.Phys.J.C 3,1(1998).。

丰田研究固态电解质的英文文献

丰田研究固态电解质的英文文献Toyota Research on Solid Electrolyte for Electric Vehicles。

In recent years, the development of electric vehicles has gained increasing attention due to the growing concern for environmental sustainability and the need to reduce greenhouse gas emissions. As a result, there has been a significant focus on improving the performance and safety of electric vehicle batteries, particularly in the area of solid electrolyte research. Toyota, as a leading automotive manufacturer, has been actively involved in the research and development of solid electrolytes for electric vehicle batteries.Solid electrolytes are a key component of next-generation batteries, offering potential advantages over traditional liquid electrolytes in terms of safety, energy density, and temperature stability. Toyota's research on solid electrolytes aims to address the challenges associated with current lithium-ion batteries, such as the risk of thermal runaway and limited energy density. By developing solid electrolytes with enhanced conductivity and stability, Toyota seeks to improve the overall performance and safety of electric vehicle batteries.One of the key areas of focus in Toyota's research on solid electrolytes is the development of new materials with high ionic conductivity. Solid electrolytes with high ionic conductivity are essential for enabling fast charging and discharging of batteries, as well as for improving their overall energy efficiency. Toyota's research efforts have led to the discovery of novel materials and fabrication techniques that have shown promising results in improving the ionic conductivity of solid electrolytes.In addition to enhancing ionic conductivity, Toyota's research also aims to improve the mechanical and chemical stability of solid electrolytes. This is crucial for ensuring the long-term reliability and safety of electric vehicle batteries, particularly under extreme operating conditions. By developing solid electrolytes that are resistant to mechanical deformation and chemical degradation, Toyota seeks to extend the lifespan of electric vehicle batteries and enhance their overall safety.Furthermore, Toyota's research on solid electrolytes also encompasses the optimization of solid-state battery architectures. This includes the design and integration of solid electrolytes with other battery components to maximize energy density and minimize internal resistance. By leveraging its expertise in battery technology and materials science, Toyota aims to develop solid-state batteries that offer superior performance and safety compared to conventional lithium-ion batteries.Overall, Toyota's research on solid electrolytes for electric vehicles represents a significant step towards the advancement of battery technology. Through its innovative approaches to material design, fabrication, and battery architecture, Toyota is driving the development of next-generation batteries that are safer, more efficient, and more reliable. As the demand for electric vehicles continues to grow, Toyota's research on solid electrolytes is poised to make a meaningful impact on the future of sustainable transportation.In conclusion, the research and development of solid electrolytes for electric vehicle batteries is a critical area of focus for Toyota. By addressing the challenges associated with current lithium-ion batteries and leveraging its expertise in battery technology and materials science, Toyota is making significant strides towards the advancement of next-generation batteries. With its commitment to improving the performance and safety of electric vehicles, Toyota's research on solid electrolytes is poised to play a pivotal role in shaping the future of sustainable transportation.。

SAT物理单词

absolute/'æbsəlu:t/ acceleration/æk͵selə'reiʃən/ 绝对加速度absolute/'æbsəlu:t/ error/'erə/ 绝对误差absolute/'æbsəlu:t/motion/'məuʃən/ 绝对运动absolute/'æbsəlu:t/ temperature /'temprıtʃə(r)/绝对温度absolute/'æbsəlu:t/velocity/vi'lɔsiti/ 绝对速度absolute/'æbsəlu:t/ zero 绝对零度absorption/əb'sɔ:pʃən/ 吸收absorptivity 吸收率accelerated/æk'seləreitid/ motion/'məuʃən/ 加速运动acceleration of gravity 重力加速度acceleration 加速度accidental error 偶然误差acoustics 声学acting force 作用力adjustment 调节aether 以太air pump 抽气机air table 气垫桌air track 气垫导轨alternating current circuit 交流电路alternating current generator 交流发电机alternating current 交流电altimeter 测高仪ammeter 安培计amperemeter 电流计ampere 安培Ampere's experiment 安培实验Ampere's force 安培力Ampere's law 安培定律amperemeter 安培计amplitude 振幅angle of rotation 自转角，转动角angular acceleration 角加速度angular displacement 角位移angular velocity 角速度anion 负离子anisotropy 各向异性annihilation 湮没anode 阳极antenna 天线applied physics 应用物理学Archimedes principle/'prinsəpl/阿基米德原理area 面积argumentation 论证argument 辐角astigmatoscope 散光镜atomic nucleus 原子核atomic physics 原子物理学atomic spectrum 原子光谱atomic structure 原子结构atom 原子Atwood ' s machine 阿特伍德机average power 平均功率average velocity 平均速度Avogadro constant 阿伏加德罗常数Avogadro law 阿伏加德罗定律balance 天平ballistic galvanometer 冲击电流计band spectrum 带状谱barometer 气压计basic quantity 基本量basic units 基本单位battery charger 电池充电器battery,accumulator 蓄电池battery 电池组beam 光束betatron 电子感应加速器Bohr atom model 玻尔原子模型boiling point 沸点boiling 沸腾bounce 反弹bound charge 束缚电荷bound electron 束缚电子branch circuit 支路breakdown 击穿brightness 亮度buoyancy force 浮力calorifics 热学camera 照相机capacitance 电容capacitor 电容器capillarity 毛细现象cathode ray 阴极射线cathode-ray tube 阴极射线管cathode 阴极cation 正离子cell 电池Celsius scale 摄氏温标centre of gravity 重心centre of mass 质心centrifugal force 离心力centripetal acceleration 向心加速度centripetal force 向心力chain reaction 链式反应chaos 混沌characteristic spectrum 特征光谱charged body 带电体charged particle 带电粒子charge 充电circular hole diffraction 圆孔衍射circular motion 圆周运动classical mechanics 经典力学classical physics 经典物理学cloud chamber 云室coefficient of maximum static friction 最大静摩摩系数coefficient of restitution 恢复系数coefficient of sliding friction 滑动摩擦系数coefficient 系数coherent light 相干光源coil 线圈collision 碰撞component force 分力component velocity 分速度composition of forces 力的合成composition of velocities 速度的合成compression 压缩concave lens 凹透镜concave mirror 凹面镜concurrent force 共点力condensation 凝结condenser 电容器conducting medium 导电介质conductor 导体conservative force field 保守力场conservative force 保守力constant force 恒力constant 常量continuous spectrum 连续谱convergent lens 会聚透镜convex lens 凸透镜convex mirror 凸面镜coordinate system 坐标系coplanar force 共面力Corolis force 科里奥利力corpuscular property 粒子性corpuscular theory 微粒说Coulomb force 库仑力coulomb 库仑Coulomb's law 库仑定律counter 计数器creation 产生creepage 漏电crest 波峰critical angle 临界角critical resistance 临界电阻critical temperature 临界温度crystal 晶体current density 电流密度current element 电流元current source 电流源current strength 电流强度curvilinear motion 曲线运动cyclotron 回旋加速器damped vibration 阻尼振动damping 阻尼Daniell cell 丹聂耳电池data processing 数据处理data 数据decay 衰变definition of ampere 安培的定义defocusing 散集density 密度derived quantity 导出量derived unit 导出单位dielectric 电介质diffraction pattern 衍射图样diffraction 衍射diffuse reflection 漫反射digital timer 数字计时器dimensional exponent 量纲指数dimension 量纲diode 二级管diopter 屈光度direct current, DC 直流direct impact 正碰direct measurement 直接测量discharge 放电disorder 无序dispersion 色散displacement 位移divergent lens 发散透镜Doppler effect 多普勒效应double slit diffraction 双缝衍射driving force 驱动力dry cell 干电池echo 回声eddy current 涡流effective value 有效值elastic body 弹性体elastic force 弹［性］力elasticity 弹性electric charge 电荷electric circuit 电路electric corona 电晕electric energy 电能electric field 电场electric field intensity 电场强度electric field line 电场线electric flux 电通量electric leakage 漏电electric neutrality 电中性electric potential 电位，电势electric potential difference电位差，电势差electric potential energy 电位能electric power 电功率electric quantity 电量electrification 起电electrification by friction 摩擦起电electrified body 带电体electrode 电极electrolysis 电解electrolyte 电解质electromagnetic damping 电磁阻尼electromagnetic induction电磁感应electromagnetic radiation 电磁辐射electromagnetic wave 电磁波electromagnetic wave spectrum 电磁波谱electromagnetism induction phenomenon 电磁感应现象electromagnet 电磁体electrometer 静电计electromotive force 电动势electron 电子electron beam 电子束electron cloud 电子云electron microscope 电子显微镜electron volt 电子伏特electroscope 验电器electrostatic equilibrium 静电平衡electrostatic induction 静电感应electrostatic screening 静电屏蔽elementary charge 基本电荷，元电荷energy 能量energy level 能级equilibrium 平衡equilibrium condition 平衡条件equilibrium of forces 力的平衡equilibrium position 平衡位置equilibrium state 平衡态equivalent source theorem 等效电源定理erect image 正像error 误差ether 以太evaporation 蒸发excitation 激发excitation state 激发态experiment 实验experimental physics 实验物理学external force 外力eyepiece 目镜far sight 远视Faraday cylinder 法拉第圆筒Faraday law ofelectromagnetic induction法拉第电磁感应定律Faraday's law ofelectromagnetic induct 法拉第电磁感应定律farad 法拉(电容的单位)film interference 薄膜干涉final velocity 末速度first cosmic velocity 第一宇宙速度fission 裂变fixed-axis rotation 定轴转动flotation balance 浮力秤fluid 流体focal length 焦距focusing 调焦，聚焦focus 焦点force 力forced vibration 受迫振动fractal 分形free charge 自由电荷free electron 自由电子free period 自由周期freezing point 凝固点frequency 频率friction force 摩擦力fusion 聚变galvanometer 电流计gas 气体general physics 普通物理学generator 发电机good conductor 良导体gravitation 引力gravity 重力gravitational potential energy重力势能gravity field 重力场ground earth 接地ground state 基态ground wire 地线hadron 强子half life period 半衰期heat 热heat transfer 传热henry 亨利hertz 赫兹(频率的单位)Hooke law 胡克定律humidity 湿度hydrogen 氢原子hypothesis 假设ice point 冰点ideal gas 理想气体image 像image distance 像距image height 像高imaging 成像imperfect inelastic collision非完全弹性碰撞impulse 冲量incident angle 入射角incident ray 入射线indirect measurement 间接测量induced electric current 感应电流induced electric field 感应电场induction current 感应电流induction electromotive force感应电动势induction motor 感应电动机inertia 惯性inertial force 惯性力inertial system 惯性系infrared ray 红外线infrasonic wave 次声波initial phase 初位相initial velocity 初速度input 输入instantaneous power 瞬时功率instantaneous velocity 瞬时速度instrument 仪器insulated conductor 绝缘导体insulating medium 绝缘介质insulator 绝缘体intensity of sound 声强interference 干涉interference fringe 干涉条纹interference pattern 干涉图样interferometer 干涉仪internal energy 内能internal force 内力internal resistance 内阻intonation 声调inverted image 倒像invisible light 不可见光ion beam 离子束ionization 电离irreversible process 不可逆过程isobaric process 等压过程isobar 等压线isochoric process 等体积过程isothermal 等温线isothermal process 等温过程isotope 同位素isotropy 各向同性joule 焦耳（功的单位）Joule heat 焦耳热Joule law 焦耳定律Joule' law 焦耳定律Kepler law 开普勒定律kinematics 运动学kinetic energy 动能Laplace's equation 拉普拉斯方程laser 激光，激光器law 定律law of conservation ofangular momentum 角动量守恒定律law of conservation ofenergy 能量守恒定律law of conservation of mass质量守恒定律law of conservation ofmechanical energy 机械能守恒定律law of conservation ofmomentum 动量守恒定律law of electric chargeconservation 电荷守恒定律Le Système International d `Unit ès 国际单位制(SI)lead 导线length 长度lens 透镜lens formula 透镜公式Lenz's law 楞次定律lepton 轻子Light ray 光线light source 光源light wave 光波lightning rod 避雷针light 光line spectrum 线状谱lines of current 电流线lines of force of electric field电力线liquefaction 液化liquefaction point 液化点liquid 液体longitudinal wave 纵波loop 回路Lorentz force 洛仑兹力luminous intensity 发光强度magnetic field 磁场magnetic field intensity 磁场强度magnetic field line 磁场线magnetic induction flux 磁感应通量magnetic induction 磁感应强度magnetic induction line 磁感应线magnetic material 磁性材料magnetic needle 磁针magnetic pole 磁极magnetics 磁学magnetism 磁学magnetization 磁化magnet 磁体magnification 放大率magnifier 放大镜，放大器manometer 流体压强计mass 质量mass defect 质量亏损mass-energy equation 质能方程matter 物质matter wave 物质波Maxwell's equations 麦克斯韦方程组mean speed 平均速率mean velocity 平均速度measurement 测量mechanical energy 机械能mechanical motion 机械运动mechanical vibration 机械振动mechanics 力学medium 介质melting fusion 熔化melting point 熔点metre rule 米尺microdetector 灵敏电流计micrometer caliper 螺旋测微器microscope 显微镜microscopic particle 微观粒子mirror reflection 镜面反射mirror 镜mixed unit system 混合单位制modern physics 现代物理学molar volume 摩尔体积molecular spectrum 分子光谱molecular structure 分子结构moment of force 力矩momentum of electromagnetic field 电磁场的动量momentum 动量motor 电动机multimeter 多用［电］表musical quality 音色N pole 北极natural frequency 固有频率natural light 自然光negative charge 负电荷negative crystal 负晶体negative ion 负离子negative plate 负极板network 网络neutralization 中和neutron 中子newton 牛顿（力的单位）Newton first law 牛顿第一定律Newton second law 牛顿第二定律Newton third law 牛顿第三定律nonequilibrium state 非平衡态north pole 北极nucleus force 核力nucleus of condensation 凝结核object 物object distance 物距object height 物高objective 物镜observation 观察Oersted's experiment 奥斯特实验ohm 欧姆Ohm law 欧姆定律ohmmeter 欧姆计Ohm's law 欧姆定律open circuit 开路optical bench 光具座optical centre of lens 透镜光心optical fiber 光导纤维optical glass 光学玻璃optical instrument 光学仪器optical lever 光杠杆optical path difference 光程差optical path 光程(路)optically denser medium 光密介质optically thinner medium 光疏介质optics 光学orbit 轨道order 有序oscillograph 示波器output 输出overweight 超重parallel connection ofcondensers 电容器的并联parallelogram rule 平行四边形定律parallel-resonance circuit 并联谐振电路parameter 参量particle 质点，粒子Pascal law 帕斯卡定律path 路程peak 峰值pendulum 摆penumbra 半影perfect conductor 理想导体perfect elastic collision 完全弹性碰撞perfect inelastic collision 完全非弹性碰撞periodicity 周期性period 周期periscope 潜望镜permanent magnet 永磁体permittivity of vacuum 真空介电常数permittivity 电容率phase 位相phenomenon 现象photocurrent 光电流photoelectric cell 光电管photoelectric effect 光电效应photoelectron 光电子photography 照相术photon 光子physical balance 物理天平physical quantity 物理量physics 物理学piezometer 压强计pitch 音调Planck constant 普朗克常量plasma 等离子体point charge 点电荷polarization 偏振polarized light 偏振光polycrystal 多晶体poor conductor 不良导体positive charge 正电荷positive crystal 正晶体positive ion 正离子positive plate 正极板positron 正电子potential energy 势能potentiometer 电位差计power 功率pressure 压强，压力primary coil 原线圈principle of constancy oflight velocity 光速不变原理prism 棱镜projectile 抛体projectile motion 抛体运动projector 投影仪proton 质子pulley 滑轮pulley block 滑轮组quantity of heat 热量quantization 量子化quantum 量子quantum mechanics 量子力学quantum number 量子数radar 雷达radioactive source 放射源radius of gyration 回旋半径random motion 无规则运动range 量程rated voltage 额定电压reacting force 反作用力real image 实像real object 实物reasoning 推理recoil 反冲rectilinear motion 直线运动reference frame 参考系，坐标系reference system 参考系reflected angle 反射角reflected ray 反射线reflection coefficient 反射系数reflection law 反射定律reflectivity 反射率refracted angle 折射角refracted ray 折射线refraction law 折射定律refraction coefficient 折射系数refractive index 折射率relative acceleration 相对加速度relative error 相对误差relative motion 相对运动relative velocity 相对速度relativity 相对论resistance 电阻resistance box 电阻箱resistivity 电阻率resistor 电阻［器］resolution of force 力的分解resolution of velocity 速度的分解resonance 共振，共鸣resonant frequency 共振频率resultant force 合力resultant velocity 合速度reversibility of optical path光路可逆性reversible process 可逆过程rheostat 变阻器right-hand screw rule 右手螺旋定则rocker 火箭rotating magnetic field 旋转磁场rotation 自转，转动Rutherford scattering 卢瑟福散射Rutherford ［α-particlescattering］experiment 卢瑟福［α散射］实验S pole 南极saturation 饱和scalar 标量scalar field 标量场scanner 扫描器second cosmic velocity 第二宇宙速度selective absorption 选择吸收self-induced electromotiveforce 自感电动势self-inductance 自感self-induction phenomenon自感系数semiconductor 半导体semi-transparent film 半透膜sensitive galvanometer 灵敏电流计sensitivity 灵敏度sensitometer 感光计sensor 传感器series connection ofcondensers 电容器的串联series-resonance circuit 串联谐振电路short circuit 短路short sight 近视shunt resistor 分流电阻significant figure 有效数字simple harmonic motion(SHM) 简谐运动simple harmonic wave 简谐波simple pendulum 单摆single crystal（monocrystal）单晶体single slit diffraction 单缝衍射sinusoidal alternating current简谐交流电sinusoidal current 正弦式电流sliding friction 滑动摩擦slit 狭缝solar cell 太阳能电池solenoid 螺线管solidification 凝固solidifying point 凝固点solid 固体solution 溶液solvation 溶解sonar 声纳sound source 声源sound velocity 声速sound wave 声波sound 声［音］source 电源south pole 南极space 空间spark discharge 火花放电special relativity 狭义相对论specific heat capacity 比热容spectacles 眼镜spectral analysis 光谱分析spectral line ［光］谱线spectrograph 摄谱仪spectrography 摄谱学spectroscopy 光谱学spectrum 光谱speed 速率spherical mirror 球面镜spontaneous radiation 自发辐射spring balance 弹簧秤stability 稳定性stabilized current supply 稳流电源stabilized voltage supply 稳压电源standard atmospheric pressure 标准大气压standard cell 标准电池standing wave 驻波static friction 静摩擦stationary state 定态steady current 恒定电流steady current source 恒流源steady voltage source 恒压源steam point 汽点stiffness 劲度［系数］stimulated radiation 受激辐射stop watch 停表sublimation 升华superconductivity 超导［电］性superconductor 超导体superposition principle ofelectric field 电场强度叠加原理superposition theorem 叠加定律supersaturation 过度饱和supersonic speed 超声速supersonic wave 超声波supply transformer 电源变压器surface resistance 表面电阻switch 开关system of concurrent forces共点力系system of particles 质点系system of units 单位制systematic error 系统误差telescope 望远镜temperature 温度tension 张力the law of gravity 万有引力定律theorem 原理theorem of kinetic energy 动能定理theorem of momentum 动量定理theoretical physics 理论物理学theory 理论thermal capacity 热容［量］thermal equilibrium 热平衡thermal motion 热运动thermal transmission 传热thermodynamic scale ［oftemperature］热力学温标thermodynamic temperature热力学温度thermometer 温度计thermometric scale 温标thermonuclear reaction 热核反应thick lens 厚透镜thin lens 薄透镜third cosmic velocity 第三宇宙速度three-phase alternatingcurrent 三相［交变］电流time 时间timer 定时器，计时器torsion balance 扭秤total reflection 全反射trajectory 轨道transformer 变压器transistor 晶体管transition 跃迁translation 平移transmission line 传输线transmissivity 透射率transverse wave 横波triboelectrification 摩擦起电triode 三极管trough 波谷tuning fork 音叉turbulent flow 湍流ultrasound wave 超声波ultraviolet ray 紫外线umbra 本影undulatory property 波动性uniform dielectric 均匀电介质uniform motion 匀速运动unit 单位unit system 单位制universal constant 普适常量universal gravitation 万有引力universal meter 多用［电］表vacuum tube 真空管vacuum 真空value of amplitude 幅值vaporization 汽化variable 变量vector 矢量velocity of light 光速velocity 速度verification 验证vernier 游标vernier caliper 游标卡尺vibration 振动viewing angle 视角viewing field 视场virtual image 虚像virtual object 虚物virtual value 有效值visibility 可见度visible light 可见光voltage 电压voltage division circuit 分压电路voltaic cell 伏打电池voltmeter 伏特计voltmeter-ammeter method 伏安法volt 伏特volume 体积vortex electric field 涡旋电场watt 瓦特wave equation 波动方程wave theory 波动说wavelength 波长wave-particle dualism 波粒二象性wave 波weight 重量weightlessness 失重white light 白光work 功work function 逸出功X-ray X射线Young experiment 杨氏实验zero line 零线α-decay α衰变α-particle α粒子α-ray α射线β-decay β衰变β-ray β射线γ-decay γ衰变γ-ray γ射线。

《信息检索与应用》总复习题

《信息检索》期末复习一、单项选择题1、文摘、题录、目录等属于（B ）。

A、一次文献B、二次文献C、零次文献D、三次文献2、从文献的（B ）角度区分，可将文献分为印刷型、电子型文献。

A、内容公开次数 B 载体类型 C 出版类型 D 公开程度3、按照出版时间的先后，应将各个级别的文献排列成（C ）。

A、三次文献、二次文献、一次文献B、一次文献、三次文献、二次文献C、一次文献、二次文献、三次文献D、二次文献、三次文献、一次文献4、手稿、私人笔记等属于（C ）文献，辞典、手册等属于（C ）文献。

A、一次，三次 B 零次、二次C、零次、三次 D 一次、二次5、逻辑“与”算符是用来组配（C）。

A、不同检索概念，用于扩大检索范围。

B、相近检索概念，扩大检索范围。

C、不同检索概念，用于缩小检索范围。

D.相近检索概念，缩小检索范围。

6、利用文献后面所附的参考文献进行检索的方法称为（A）A、追溯法B、直接法C、抽查法D 综合法7、如果检索结果过少，查全率很低，需要调整检索范围，此时调整检索策略的方法有（B ）等。

A、用逻辑“与”或者逻辑“非”增加限制概念。

B.用逻辑”或“或截词增加同族概念。

C、用字段算符或年份增加辅助限制。

D、用”在结果中检索“增加限制条件。

8、根据国家相关标准，文献的定义是指“记录有关（C）的一切载体。

A、情报 B 、信息C、知识D、数据9、以作者本人取得的成果为依据而创作的论文、报告等，并经公开发表或出版的各种文献，称为（B ）A、零次文献B、一次文献C、二次文献D、三次文献10、哪一种布尔逻辑运算符用于交叉概念或限定关系的组配？（A ）A、逻辑与（AND）B、逻辑或（OR)C、逻辑非(NOT)D、逻辑与和逻辑非11、逻辑算符包括（D）算符。

A、逻辑“与”B、逻辑“或”C、逻辑“非”D、A、B和C12、事实检索包含检索课题（A ）等内容。

A、背景知识、事件过程、人物机构B、相关文献、人物机构、统治数据C、事件过程、国外文献、国内文献D、国内文献、国外文献、统计数据13、区别于一般期刊论文或者教科书，参考工具书的突出特点是（C ）。

材料导论中英文讲稿 (26)

Video 4 ToughnessNow, we learn materials’ toughness (T)韧性模量.译文: 现在我们学习材料的韧性（韧性模量）。

Toughness is the ability or capacity of a material to absorb energy during plastic deformation. As shown in the figure, modulus of toughness, equal to the total area under the stress-strain curve up to the point of rupture, represents the energy per unit volume of a material required to produce fracture under static conditions.译文: 韧性是材料在塑性变形时吸收能量的能力。

如图所示，韧性模量等于应力-应变曲线从初始到断裂点之间的面积，反映使材料发生断裂单位体积内其需要吸收的最小能量。

Toughness can also be expressed in terms of the ease or difficulty in propagating a crack. It can be measured by the amount of energy adsorbed by a material in creating a unit area of crack. A tough material has no defects in its microstructure. As shown in the figure, to stop crack, people insert fibers in a metal to form fiber metal composite to increase fiber’s toughness.Therefore, you know that having a good amount of ductility makes many materials tough because the plastic flow permitted by the ductility prevents a concentration of stress at the tip of a crack.译文: 韧性也可以表示为拓展材料上的裂痕的难易程度。

Forcite分子动力学模块计算温度对带隙和光谱的影响-文档资料

13分别是实验确定的sio依次使这四个结构文件为当前文件同时在右下角的properties中选lattice3d显示相应结构的体积和空间群
1. 2. 3.
本课程学习内容计算石英晶体晶胞体积与温度的关系，了解分子动力学的初步使用。二. 计算硅晶体晶胞体积与温度的关系，温度对带隙和光谱的影响。
石英熔点～1800K
用同样的步骤，计算200、300、400…2000K温度下的SiO2晶胞体积。课堂上只取300、800、1600K三个温度，计算晶胞体积，记下对称性。
不同温度下SiO2晶胞的体积和对称性
P6222 P3221 P6222 P6222
P6222
P3221 P6222 C2 C2 P1 P1 P1 P1 C2 P6222
用同样方法计算1000K时硅的能带和光谱
收敛性测试～模拟计算时间与晶胞体积的关系
计算1200K下-SiO2的体积，比较模拟时间对计算出的体积数值的影响，以设置合适的模拟时间。
结构文件为 sio2_1200.xsd，设为当前文件。
选择分子动力学计算模块Forcite 。从 Forcite的下拉菜单中打开Calculation对话框，选择Setup标签，设置Task为动力学 (Dynamics)，计算精度Quality为medium。
3. 以300K下Forcite计算出的硅结构为稳定构形，用第一性原理软件CASTEP计算其能带和光谱由File/Save Project保存文件；再由 Window/Close all关闭窗口文件。激活300K下Forcite计算出的硅结构，使其为当前文件。
几分钟后计算完成，出现新文件
同样对-SiO2进行结构优化，Project中出现两个新文件夹。

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b a
arXiv:cond-mat/9912075v1 [cond-mat.soft] 6 Dec 1999
We study the transversal dynamics of a charged stripe (quantum string) and show that zero temperature quantum ﬂuctuations are able to depin it from the lattice. If the hopping amplitude t is much smaller than the string tension J , the string is pinned by the underlying lattice. At t ≫ J , the string is depinned and allowed to move freely, if we neglect the eﬀect of impurities. By mapping the system onto a 1D array of Josephson junctions, we show that the quantum depinning occurs at (t/J )c = 2/π 2 . Besides, we exploit the relation of the stripe Hamiltonian to the sine-Gordon (SG) theory and calculate the infrared excitation spectrum of the quantum string for arbitrary t/J values. PACS numbers: 74.20.Mn, 74.20.-z, 71.45.Lr
1
ˆ = −2t H
cos p ˆn +
n
J 2
n
(ˆ xn+1 − x ˆn ) .
2
(2)
Hereafter, we classify the state of the quantum ˆ = string by the value of the topological charge Q xn+1 − x ˆn ). In the case of open boundary condin (ˆ tions (BC), the topological charge is an arbitrary integer, Q = 0, ±1, ±2, ... The states with positive and negative charges are called kinks (K) and antikinks (AK), respectively. Here, we consider periodic BC, x ˆN +1 = x ˆ1 . Hence, the total topological charge of the string is zero. Since we are interested in the conducting properties of the system, we have to determine the current operator ˙ n , where e is the charge of the particle and the ˆ n = ex ˆ dot denotes the time derivative. Using the equation of ˙ n = i[H, ˆ x motion x ˆ ˆn ], we obtain ˆ n = 2et sin p ˆn . At this point, it is convenient to perform a dual transformation to new variables referring to the segments of the string, i.e., to a pair of neighbour holes, x ˆn − x ˆn−1 = π ˆn , p ˆn = ϕ ˆn+1 − ϕ ˆn . (3)
Dynamics of lattice pinned charge stripes
Yu. A. Dimashkoa , C. Morais Smitha,b , N. Hasselmanna,c, and A. O. Caldeirad
I Institut f¨ ur Theoretische Physik, Universit¨ at Hamburg, D-20355 Hamburg, Germany Institut de Physique Th´ eorique, Universit´ e de Fribourg, P´ erolles, CH-1700 Fribourg, Switzerland c Dept. of Physics, University of California, Riverside, CA, 92521, USA d Instituto de F´ ısica Gleb Wataghin, Universidade Estadual de Campinas, CP 6165, 13085-970 Campinas SP, Brasil (February 1, 2008)
The existence of a striped phase in doped 2D antiferromagnets (AF) has been recently a subject of intense experimental and theoretical investigations. Experimentally, elastic1,2 and inelastic3 neutron diﬀraction measurements in nickelates1 and cuprates2,3 have revealed the presence of charge and spin-order. Besides, muon spin resonance and nuclear quadrupole resonance results4 have also been successfully interpreted within the picture of charged domain walls separating antiferromagnetic domains. Striped phases have repeatedly been found in numerical investigations of t − J and Hubbard models.5 It is possible that the striped phase is responsible for many of the unusual properties of the cuprate superconductors.6 In the present paper, we study within a phenomenological model7–9 the transversal dynamics of a single stripe (quantum string). By performing a canonical transformation in the quantum string Hamiltonian, we map the system onto a 1D array of Josephson junctions, which is known to exhibit an insulator/superconductor transition at (t/J )c = 2/π 2 . This transition is also known to represent the unbinding of vortex/antivortex pairs10 in the equivalent XY model. Further, by exploiting the relation of these models to the sine-Gordon (SG) theory11 , we study the spectrum of the quantum string in a sector of zero topological charge of its Hilbert space and reveal the meaning of the transition in the “string” language. At (t/J )c the (insulating) pinned phase, corresponding to an energy spectrum with a ﬁnite gap, turns into a (metallic) depinned phase where the spectrum becomes gapless. In doing so, we have connected two important and diﬀerent classes of problems, i.e., the transversal dynamics of stripes in doped AF and a system with the well known properties of the SG theory. Let us consider a single vertical string on a N × L square lattice (see Fig. 1a). The linear concentration of holes in the string is assumed to be one hole/site. The string is composed of N charged particles elastically interacting with the neighbour ones and constrained to