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运用密度泛函理论的超软赝势平面波方法对3C-SiC晶体结构进行了几何优化,得到与实验值相符的晶格参数,在压强为0～100 GPa范围内对3C-SiC的电子结构与弹性进行了计算,结果表明晶体结构是稳定的,且带隙随着压强的增大而减小。然后利用准谐德拜模型研究了3C-SiC在温度为0～2 100 K、压强为0～100 GPa范围内的热力学性质,结果表明其等容热容、热膨胀系数及熵函数都随温度的升高而增大,随压强的增大而减小,而德拜温度随温度的升高而减小,随压强的增大而增大。
The crystal structure of 3C-SiC was optimized by using the super-soft pseudopotential plane wave method of density functional theory, and the lattice parameters agreeing with the experimental data were obtained. The electronic structure of 3C-SiC with the pressure in the range of 0 ~ 100 GPa and The calculated elasticity shows that the crystal structure is stable and the band gap decreases with increasing pressure. Then the thermodynamic properties of 3C-SiC at temperatures ranging from 0 to 2 100 K and pressures from 0 to 100 GPa were studied by quasi-harmonic Debye model. The results show that the isotherms, thermal expansion coefficients and entropy functions of 3C-SiC are dependent on the temperature Increases with increasing pressure and decreases with increasing pressure, while Debye temperature decreases with increasing temperature and increases with increasing pressure.