高压下CaF2晶体的电子结构与光学性质

利用第一性原理超软赝势平面波的方法,对氟化钙晶体在0～400GPa范围内进行了几何优化,计算了电子结构与光学吸收谱,计算结果表明,随着压强的增大,晶格减小,能带发生展宽,带隙变大,吸收波段存在蓝移,且压强变化的影响越来越小。     

高压下翠绿亚胺聚合物的理论吸收谱

利用改进的Ginder-Epstein模型计算了翠绿亚胺聚合物在参数V4,0取值于1.8～35.8eV的自洽变分基态并通过芳环扭角的变化来估算聚合物压强,给出了V4,0、芳环扭角及能隙与理论压强之间的变化关系,并作出了不同理论压强下的理论吸收谱.结果表明,随此参数的增大芳环扭角和能隙都缩减而理论压强升高.当理论压强由零压增至饱和压强3.0GPa左右时,翠绿亚胺聚合物π-π*吸收峰由2.01eV蓝移至最小值0.87eV.此理论谱供压力定标参考.     

高压对含Zn_i的ZnO结构及光电性质的影响

基于DFT的第一性原理计算含间隙锌Zni点缺陷的Zn O体系的晶体结构、电子结构及光学性质随压强变化的规律.结果表明,晶格常数随压强增加而线性减小,原因是压力的增加导致晶胞体积减小.对电子结构和光学性质的研究发现,体系的最小带隙宽度随压强的增加而线性增加,光谱的峰位随压强的变化出现不同的能移,在3.0~4.7 e V光子能量范围内,压强变化对介电峰和吸收峰强度的影响显著.1     

外磁场中理想自由电子气体的压强

文章中用路径积分方法计算了非退化理想电子气体在均匀外磁场中的配分函数．从而计算了热力学压强、外磁场存在时力学压强与热力学压强不同     

高压下ZrB_2的结构和热力学性质的第一性原理计算

利用平面波赝势密度泛函理论计算了ZrB2的基本参数,包括晶格常数、体弹模量、体弹模量对压强的一阶导数,同时通过准谐德拜模型研究了ZrB2热力学性质,给出了不同压强和不同温度下的热容和德拜温度的计算值,发现热容随着压强增加而减小,德拜温度随压强增加而增加.     

高压下GaAs和AlAs结构及弹性性质的第一原理计算

基于第一性原理平面波超软赝势密度泛函理论方法计算了ZB-GaAs,RS-GaAs,CsCl-GaAs,NiAs-GaAs,WZ-GaAs和ZB-AlAs,RS-AlAs,NiAs-AlAs的结构参数、体弹模量及体弹模量对压强的一阶导数.计算了GaAs和AlAs在不同压强下的弹性常数,以及不同结构间的相变压强.得到了比较满意的计算结果.     

光泵NH3分子亚毫米波激光的模式竞争

采用半经典密度矩阵理论研究了光泵NH3分子亚毫米波激光的P支跃迁(V2∶a→sP(5,4))和Q支跃迁(V2∶a→sQ(5,4))的模式竞争.推导了四能级系统的激光介质的增益表达式;采用迭代法,数值计算了不同工作条件下的P支跃迁和Q支跃迁的输出光强,得到了模式竞争的规律:在压强较低的情况下,P支跃迁占优势;在压强较高情况下,Q支跃迁占优,但光强很弱并受到严重的自吸收效应所抑制.计算结果与实验相符.     

压板间隙△对导轨压强的影响

本文寻出了压板间隙△对机床导轨压强分布影响的计算方程式,使迄今为止△量大小对压强影响的定性分析转入了定量分析,为调整合理的△提供了理论依据,并给出了计算实例.     

高压下GaN的光学特性

根据密度泛函理论,采用平面波赝势和广义梯度方法,研究了闪锌矿结构的GaN晶体在不同压强下的光学性质。结果表明,随着压强的增大,直接带隙和间接带隙都逐渐增大;在外界压强为125 GPa时,GaN从直接带隙半导体变成间接带隙半导体,吸收波段出现了蓝移的现象。     

废旧混合塑料自动识别分选机喷嘴装置实验研究

为确定废旧混合塑料自动识别分选机上喷嘴的最佳形状,我们首先分析得出输出压强是分选塑料的关键,并计算出最小输出压强.然后讨论影响输出压强的相关参数,通过计算和模拟得出输出压强相对输入压强的衰减程度,初步估算输入压强.然后通过实验获取相同输入压强下输出压强随喷嘴直径及管长变化的数据,用相关系数法总结绘制出直径和管长与输出压强的关系曲线.对实验数据进行拟合度分析,选取最佳的喷嘴参数.最后对其喷射范围进行测量,给出具体的喷嘴分布方案.     

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.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

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     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of