有机分子构型对其电学性质的影响

以化学吸附于金原子团簇的4,4′-二巯基二苯醚分子为研究对象,用从头算方法和弹性散射格林函数理论,对分子中两个苯环的构型变化对其电学性质所带来的影响进行了研究.计算结果表明,随着构型的变化,分子轨道的能级发生移动,分子的电流、电导以及分子与电极的耦合系数也有相应的变化;但以两个苯环共面时导电性能最佳,垂直时最差.     

4，4’二硫基二苯醚分子导线I - V特性的第一性原理研究

利用第一性原理和非平衡格林函数的方法对4,4'二硫基二苯醚分子电输运特性的研究结果表明,电流随着外加电压的增加而增加.对于一个确定的电子传导通路,电子通过分子桥的概率与电子能量是紧密相关的.随着电子能量的变化,电子通过分子桥的概率呈现震荡形式.     

多散射杂质对二维电子系统输运特性的影响

利用散射矩阵理论研究了含有多个矩形散射杂质二维系统中电子输运问题.绝对零度下,电导随入射电子能量增大,呈台阶式上升形式;杂质宽度的减小使得电导的量子化现象增强;杂质长度的增大,使得电导在最初阶段急剧减小,而后呈现周期性振荡;随着散射杂质数量的增加,电导由急剧减小也呈现周期性振荡.温度的升高使得电导台阶倾斜,量子化现象逐...     

侧链位阻效应对芴基分子电导的影响研究

为了研究侧链对多苯环芴基分子电导的影响,我们采用扫描隧道显微镜裂结(STM-BJ)技术对分子骨架相同但侧链不同的一系列芴基分子的单分子电导进行测量,同时利用循环伏安法(CV)和密度泛函理论(DFT)计算对分子进行表征.研究表明,3种分子均产生高低不同的两类电导值,其中它们的低电导基本一致,而高电导之间产生明显的差别.高电导的差别可能是分子侧链产生的空间位阻阻碍了分子骨架上的电荷传导,进而使分子结电导减小.本研究有助加深对分子侧链影响单分子结电导的理解.     

气相丙酮分子与带电离子的低激发态特性

采用密度泛函理论中的B3P86方法,在6-311++G(d,p)基组水平上,优化气相丙酮分子及带电离子的基态稳定几何构型,并用含时密度泛函理论(TD-DFT)方法,研究气相丙酮分子和离子的低激发态特性.结果表明:随着分子获得电子数目的增加,体系能量逐渐增加;S1激发态能量与基态能量差值ΔE减小;分子荧光波长急剧增加;电子跃迁轨道数减少.     

推、拉电子基团对水杨醛缩苯胺及其衍生物分子的电子结构和非线性光学性质的影响

采用量子化学半经验FF/ PM3方法,讨论了水杨醛缩苯胺分子中两个苯环的对位被推、拉电子基团取代后,体系电子结构和非线性光学性质的变化.考察了分子的电子结构对非线性光学性质影响的微观本质,结果表明:得到的具有配体-共轭桥键-受体型结构的水杨醛缩苯胺分子显示了良好的非线性光学性质.     

人造双原子分子的自旋极化电子输运

利用非平衡格林函数方法研究了Aharonov-Bohm环中人造双原子分子的自旋极化电子输运性质.计算了量子点中自旋相关的占有数、自旋积累以及系统总电导和自旋极化率.发现两电极之间的耦合强度以及量子点之间的耦合强度对系统自旋相关输运性质以及总的电导有重要影响.     

梯子形石墨烯纳米条带输运性质的研究

在紧束缚近似下,采用Green函数和Landauer-Büttiker公式计算了梯子型石墨烯纳米条带的电子输运性质。结果表明,随着阶梯数的增加,梯子型石墨烯纳米条带电导峰以0.0 eV为中心发生对称分裂,中心电导峰减小直至消失;随着阶梯间间隔变大,电导峰减小。通过数值计算,揭示了该新型石墨烯结构电子输运的物理机制,为基于石墨烯的新器件的设计和优化提供理论指导。     

气相Val分子与带电离子低激发态特性的理论研究

采用密度泛函B3LYP方法,所有C、O、N、H原子在6-311+G(2df)基组水平上,优化气相Val中性分子和带电离子基态稳定几何构型.在6-311++G(d,p)基组水平上,采用TD-DFT方法,研究气相Val中性分子、离子低激发态的特性.结果表明:随着分子获得电子数目的增加,体系能量逐渐增加;S1激发态能量与基态能量差值ΔE减小;分子荧光波长急剧增加;S2激发态电子跃迁轨道数没有改变.     

压力对分子结电输运性质的影响

在密度泛函理论基础上,优化不同金电极距离下以羧基为末端基团的硫醇分子的几何结构,得到了体系能量与金电极距离的变化关系。根据外力与能量的关系式,计算了不同金电极距离下对应的压力值。利用弹性散射格林函数方法计算了不同压力下分子结的伏安曲线。研究结果表明,当两个金电极距离被拉伸为2.08 nm时,羧基断开了与金电极的物理接触。随着外加压力的增加,分子结的电导值快速地增加。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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