SiC相变和热动力学性质的第一性原理计算(英文)

利用基于密度泛涵理论的全势能线性糕模轨函法计算了闪锌矿(ZB)和岩盐(RS)结构的SiC的相变和热动力学性质.结果发现SiC从ZB结构到RS结构的相变压力为55.9GPa,与其他计算结果一致.通过实验测得SiC在高温高压条件下的性质存在较大困难,因此基于准谐德拜模型本文研究了ZB结构和RS结构的热动力学性质,并且成功得到了相对体积V/V_0随压强P,热膨胀系数随温度T,德拜温度■和热容Cv随压强,以及热容随温度的变化关系,其中相对体积V/V_0随压强P的变化关系与实验结果吻合的较好.

Transition phase and thermodynamic properties of SiC via first-principles calculations

The phase transition and thermodynamic properties of SiC in zine-blende(ZB)and rock-salt(RS)structures are calculated by performing the full-potential linearized muffin-tin orbital(FP-LMTO)scheme in the frame of density functional theory.The transition phase of SiC from the ZB structure to the RS structure occurs at the pressure of 55.9 GPa,which consists with other calculated values.There is a great difficulty in obtaining the properties of high temperature and pressure of SiC through experiments,therefore in this work the thermodynamic properties of the ZB and RS structures are studied through the quasi-harmonic Debye model.The dependences of the relative volume V/V0 on the pressure P,the thermal expansions on the temperature,the Debye temperature θ and heat capacity Cv on the pressure P,as well as the heat capacity Cv on the temperature T are also successfully obtained,among which the dependence of the relative volume V/V0 on the pressure P is consistent with xperimental result.