运用密度泛函理论方法,采用MS中CASTEP模块计算了铀晶体的能量随体积变化的关系,并绘制了E-V曲线。运用准谐振子德拜模型计算了压强从0~100GPa、温度从0~2000K下的晶体铀的相对体积,发现相对体积随着温度和压强的增加而减小。并成功得到了热膨胀系数、热容、以及体弹模量随温度和压强的变化关系。预测了铀的热力学性质。为铀晶体在高温高压下的实验研究提供了理论依据。

The total energy of uranium crystal with the change of volume was calculated by using CASTEP module based on the density function theory. The E-V curve was gotten. Through the quasi-harmonic Debye model, the thermodynamic properties of uranium, such as the thermal expansion coefficientα, the heat capacity Cv, the relative volume V/V0 and the bulk modulus B, were studied in the range of pressure up to 100GPa and temperature up to 2000K. The thermodynamic properties of uranium were predicted. The result could provide theory evidence for the experimental investigation of uranium crystal under high temperature and high pressure.

高岭石广泛应用于化工填料和吸附材料等领域，是重要的非金属矿产物质。本文基于密度泛函理论，采用平面波超软赝势方法，利用CASTEP软件对其电子结构进行量化计算。比较了截断能分别取为450eV、500eV、550eV时的优化结果，得出截断能取为500eV时结果较理想；接着对GGA-PW91、GGA-PBE和LDA-CA-PZ三种交换关联函数进行分析，最终选取GGA-PW91作为交换关联函数。晶格常数的计算值与实验值符合较好。量化计算结果表明：高岭石是一种宽能隙绝缘体，其靠近费米能级处的价带部分主要由O原子的s态和p态电子决定，导带主要有Si和Al的sp态电子和H的s态电子决定。为进一步分析高岭石表面性质提供依据。

Kaolinite is widely applied in areas such as chemical packing and adsorption material, is an important nonmetallic mineral substance. The electronic structure of bulk kaolinite was calculated using density functional theory(DFT)method of plane-wave pseudo-potential method in CASTEP. The calculated values of the lattice constant of kaolinite were compared with the experimental values when using cut energy 450, 500, 550eV, respectively, the 500 eV gave relatively ideal results; Then GGA-PW91, GGA-PBE and LDA-CA-PZ three exchange correlation functions were analyzed, and finally select GGA-PW91 exchange correlation functions. The calculation of lattice constant values coincide well with the experimental values. The quantitative calculation results show that, the kaolinite is a kind of wide band gap energy insulators, its valence band which is near the Fermi energy is decided by O sp states , conduction band is mostly decided by sp state of Si and Al atoms and Hs state. This resul

通过基于密度泛函理论的第一性原理计算方法,对MgCu2,Mg2Ca和MgZn2的力学性能和电子结构进行计算,计算所得晶格参数与实验值和文献值相吻合。合金形成热和结合能的计算结果表明,MgCu2具有最强的合金形成能力和结构稳定性。计算了MgCu2,Mg2Ca和MgZn2的弹性常数,推导了体模量、剪切模量、弹性模量和泊松比。结果表明,MgCu2、Mg2Ca和MgZn2均为延性相,MgCu2的刚度最大,MgZn2的塑性最好。通过对结合能和弹性常数的计算,预测了MgCu2、Mg2Ca和MgZn2的熔点。通过对态密度（DOS）、Mulliken布居数、电子占据数和差分电荷密度的计算,分析了MgCu2、Mg2Ca和MgZn2的结构稳定性和力学性能机制。最后,计算和讨论了3种金属间化合物的Debye温度。

Mechanical properties and electronic structure of MgCu2, Mg2Ca and MgZn2 phases were investigated by means of first principles calculations from CASTEP program based on density functional theory (DFT). The calculated lattice parameters are in good agreement with the experimental and literature values. The calculated heat of formation and cohesive energies showed that MgCu2 has the strongest alloying ability and structural stability. Elastic constants of MgCu2, Mg2Ca and MgZn2 were calculated, and the bulk moduli, shear moduli, elastic moduli and Poisson ratio were derived. The calculated results show that MgCu2, Mg2Ca and MgZn2 are all ductile phases. Among the three phases, MgCu2 has the strongest stiffness and the plasticity of MgZn2 phase is the best. Melting points of the three phases were predicted using cohesive energy and elastic constants. Density of states (DOS), Mulliken population, electron occupation number and charge density difference were discussed. Finally, De