固氩高压物态方程和弹性性质的密度泛函理论计算

 用平面波赝势方法结合局域密度近似密度泛函理论（DFT-LDA）计算了零温下固态氩晶体在压力0~82 GPa的p-V关系和弹性性质,计算结果与静高压实验数据符合较好,计算结果表明局域密度近似方法能较好地描述固氩晶体高压下的性质,采取合理的方法和计算参数,惰性气体固态晶体高压下的力学性质可以比较准确地计算出来,这可为一些还不能通过实验进行研究的物态分析提供借鉴。     

高压下TATB压缩性质的LDA和GGA比较研究

本文采用第一性原理密度泛函理论,结合平面波赝势方法,采用局域密度近似(LDA)和广义梯度近似(GGA)两种方法计算了TATB晶体在高压(0~7 GPa)压缩下的结构和物理性质,并与实验数据进行了比较.详细讨论了TATB晶体的晶体结构和分子构型随压力的变化.     

高压下ZnSe的电子结构和光学性质

运用密度泛函理论体系下的平面波赝势(PWP)和广义梯度近似(GGA)方法,利用第一性原理计算了不同的压强下ZnSe晶体闪锌矿结构,得到了它的平衡晶格常数、总能量、电子态密度分布、能带结构、光反射与吸收系数等性质,详细讨论了高压下ZnSe的电子结构,并且结合实验结果定性地分析了高压下的光学性质. 关键词： 闪锌矿结构 态密度 能带结构 密度泛函理论     

2H-PbI_2晶体的电子结构和力学性质

采用基于密度泛函平面波赝势方法(PWP)方法,计算了六角晶系2H-PbI2晶体的电子结构、力学性质和硬度.采用局域密度近似(LDA)方法计算的晶格常数、带隙、弹性常数与实验值和理论值符合较好.计算表明,2H-PbI2是一种直接带隙的半导体,带隙大约为2.38eV.运用复杂晶体硬度计算公式计算了六角晶系2H-PbI2晶体的硬度,硬度值大约为2.54GPa.还发现2H-PbI2晶体的各向异性非常明显.     

2H-PbI2晶体的电子结构和力学性质

采用基于密度泛函平面波赝势方法(PWP)方法,计算了六角晶系2H-PbI2晶体的电子结构、力学性质和硬度。采用局域密度近似(LDA)方法计算的晶格常数、带隙、弹性常数与实验值和理论值符合较好。计算表明,2H-PbI2是一种直接带隙的半导体,带隙大约为2。38eV。运用复杂晶体硬度计算公式计算了六角晶系2H-PbI2晶体的硬度,硬度值大约为2. 54 GPa。还发现2H-PbI2晶体的各向异性非常明显。     

高压下MgS的弹性性质、电子结构和光学性质的第一性原理研究

采用基于密度泛函理论(density functional theory)基础上的第一性原理赝势平面波方法, 计算研究了MgS晶体B2构型在不同压强下的几何结构、弹性性质、电子结构和光学性质. 计算结果表明, 在高压作用下, 该结构的导带能级有向高能级移动的趋势, 而价带能级有向低能级移动的趋势. 同时, 对照态密度分布图及高压下能级的移动情况, 分析了MgS B2构型在高压作用下的光学性质, 发现高压作用下, 吸收光谱发生了明显的蓝移.     

VO_2晶体电子结构及其掺杂的第一性原理研究

运用密度泛函平面波赝势(PWP)和广义梯度近似(GGA)方法,对二氧化钒(VO2)两种不同晶体电子结构进行了计算.研究了低温单斜晶型和高温四方晶型结构的VO2电子态密度(DOS)和能带(energyband)结构,通过分析发现,四方晶的金属性比较明显,这是由于电子态密度和能带结构分析结果表明不同特性产生的原因是V原子的3d电子贡献不同导致的.本文中我们还将部分O原子替换为F原子后对单斜晶替位掺杂进行了的计算讨论,本文的计算结果都较好地符合实验结果,表明密度泛函平面波赝势和广义梯度近似方法可以用来描述VO2的结构和性质.我们认为,这种方法应用于描述氧化物的电子结构和性质是一种新的探索.     

NaNO_2晶体线性和非线性光学系数的计算

使用从头计算平面波赝势方法,计算了NaNO2晶体电子能带结构,并使用改进的倍频公式计算了它的线性折射率和静态二级非线性系数,所得到的结果和实验值相符.采用实空间原子切割方法分析了阳离子和阴离子基团对光学性质的贡献.计算表明(NO2)-基团对双折射率和倍频系数的贡献占主要地位,从而进一步验证了阴离子基团理论的正确性.     

高压下固态Kr弹性性质、电子结构和光学性质的第一性原理计算

采用密度泛函理论中平面波基矢,模守恒赝势结合局域密度近似以及广义梯度近似对固态Kr在高压下的结构以及弹性性质进行了研究, 通过计算发现弹性常数,Debye温度以及声速都随压力的增大而增大,所计算的弹性常数与实验和其他的理论符合的很好. 利用Debye模型得到了固态Kr的热力学性质, 熵随压力的增大而减小,随温度升高而升高;而定容热容C_v,定压热容C_p则随温度升高而升高,而且C_v在达到一定温度时趋于定值,所得的热力学性质和实验值是相符的．最后还预测了固态Kr在高压下的电子结构和光学性质, 计算结果表明随压力的增加固态Kr的前沿能带变窄,光吸收系数增大,吸收峰增宽,电子更容易发生跃迁,固态Kr有可能转化为半导体． 关键词： Kr 第一性原理 弹性常数 光学性质     

γ-Si3N4在高压下的电子结构和物理性质研究

采用基于密度泛函平面波赝势方法(PWP)和广义梯度近似(GGA-PW91),计算了不同压强下γ-Si3N4的电子结构、光学性质和力学性质.基于计算结果,分析讨论了γ-Si3N4各物理参数随外压力的变化规律.计算表明,γ-Si3N4是一种适合于在高压条件下工作的材料.     

Calculation of energy characteristics of the metal surface taking into account the lattice relaxation effects

Within the framework of the electron-density functional theory method, a self-consistent calculation of the shift of two near-surface ionic planes in different metals has been carried out. The effect of the near-surface lattice relaxation on the surface energy of metals and on the electron work function from these metallic surfaces has been investigated. To describe the arising strong inhomogeneity of the electronic system in the near-surface region, gradient corrections have been taken into account for the kinetic and exchange-correlation energy. To calculate the effect of electron-ion interaction on the energy characteristics of the surface, the Heine-Abarenkov pseudopotential has been used.     

用赝势方法计算某些简单金属的状态方程

本文提出了一种确定简化的Heine-Abarenkov模型赝势参数的新方法,使用零温、零压下晶体的体积模量和晶格常数的实验值来确定赝势参数γ_c以及电子-离子平均相互作用能的修正系数H。用这种模型势和二阶微扰理论计算了十一种简单金属的状态方程。在293K计算出的压力-体积关系与实验数据进行了比较。除了Zn在不同实验数据之间本身就偏离较大外,理论与实验的符合都比较好。 关键词：     

液态铅的电阻率计算

根据费米面实验数据修正Behari关于液态铅的模型赝势,构建新的模型赝势,结合实验结构因子及硬球结构因子,计算不同温度下液态铅的电阻率,计算结果与实验数据较为符合,并对计算过程中的误差及模型赝势的适用性进行了分析. 关键词： 电阻率计算 电子输运 液态铅 模型赝势     

Effect of three-body forces on the lattice dynamics of noble metals

A simple method to generate an effective electron-ion interaction pseudopotential from the energy wave number characteristic obtained by first principles calculations has been suggested. This effective potential has been used, in third order perturbation, to study the effect of three-body forces on the lattice dynamics of noble metals. It is found that three-body forces, in these metals, do play an important role. The inclusion of such three-body forces appreciably improves the agreement between the experimental and theoretical phonon dispersion curves.     

A model pseudopotential and energy wave number characteristics of simple metals

A model pseudopotential for electron-ion interaction in simple metals is proposed. The screened form factors of the potential are presented for 25 simple metals. Using this model potential, the energy wave number characteristics for these metals are determined. For sodium, potassium and lead, the results are compared with the numbers obtained from the analysis of experimental phonon frequencies and other theoretical calculations.     

Calculation of the temperature-dependent energy characteristics of adsorption systems based on transition metals

Self-consistent calculations of the temperature-dependent absorption energy and electron work function on the surface of absorption systems based on transition metals have been performed via the electron-density functional method. The influence of substrate surface relaxation on the energy characteristics of adsorption systems is investigated. Gradient corrections to kinetic and exchange-correlation energies are estimated to describe a strong inhomogeneity arising in the electron system of the subsurface region. The influence of electron-ion interaction on energy characteristics is calculated with the use of the Ashcroft pseudopotential. The temperature-dependent formation of various adsorption structures from transition metal atoms is discussed.     

Linear potential and phonons in calcium and strontium

The success recently achieved by the linear form of electron-ion pseudopotential in the case of alkalies, Al and Pb has led to further apply it to the bivalent metals, Ca and Sr, for the calculation of phonon propagation along the three symmetry directions. The results obtained compare well with the value based on the more sophisticated formulations of Animalu and Moriarty. The reliability of these results is confirmed through an excellent reproduction of the experimental binding energy and compressibility. A succesful prediction of elastic constants further highlights the usefulness of the present simple approach.     

Investigation of cavitation bubble collapse in hydrophobic concave using the pseudopotential multi-relaxation-time lattice Boltzmann method

The interaction between cavitation bubble and solid surface is a fundamental topic which is deeply concerned for the utilization or avoidance of cavitation effect.The complexity of this topic is that the cavitation bubble collapse includes many extreme physical phenomena and variability of different solid surface properties.In the present work,the cavitation bubble collapse in hydrophobic concave is studied using the pseudopotential multi-relaxation-time lattice Boltzmann model(MRT-LB).The model is modified by involving the piecewise linear equation of state and improved forcing scheme.The fluid-solid interaction in the model is employed to adjust the wettability of solid surface.Moreover,the validity of the model is verified by comparison with experimental results and grid-independence verification.Finally,the cavitation bubble collapse in a hydrophobic concave is studied by investigating density field,pressure field,collapse time,and jet velocity.The superimposed effect of the surface hydrophobicity and concave geometry is analyzed and explained in the framework of the pseudopotential LBM.The study shows that the hydrophobic concave can enhance cavitation effect by decreasing cavitation threshold,accelerating collapse and increasing jet velocity.     

Corrections to the Landau diamagnetism of liquid metals

Perturbation corrections to the free electron value of the Landau susceptibility have been obtained in terms of an electron-ion pseudopotential and the structure factor of the liquid metal.