3C-SiC的结构和热力学性质

Structures and Thermodynamic Properties of 3C-SiC Compound

利用第一性原理平面波模守恒赝势密度泛函理论研究了3C-SiC的结构,其零温(0K)零压下的晶格常数、体弹模量及其对压强的一阶导数、弹性常数的计算结果与实验值和其它理论计算结果相符合.通过准谐德拜模型,得到了不同温度不同压强下的热容和德拜温度,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,并成功地获得了相对晶格常数、相对体积、体弹模量、热膨胀系数与温度和压强的关系.

By using first-principles plane-wave normconserving pseudopotential method of density functional theory, the structures and thermodynamic properties of 3C-SiC were investigated. The calculated lattice parameters, bulk modulus, the first order pressure derivative of bulk modulus, and elastic constants are consistent with the experimental data and those calculated by others. Through the quasi-harmonic Debye model, Debye temperature and heat capacity under different temperatures and pressures were successfully obtained. It is shown that when the temperature is constant, the Debye temperature increases almost linearly with applied pressures, while the heat capacity shows an opposite trend. The relative lattice parameters and relative volume, the bulk modulus, thermal expansion versus temperature and pressure were also investigated.