关键词: 密度泛函理论, 准谐德拜模型, 热力学性质

Abstract: 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.

Key words: Density functional theory, Quasi-harmonic Debye model, Thermodynamics properties