高压下CaPo弹性性质和热力学性质的第一性原理研究

利用密度泛函理论的平面波赝势方法预测研究了CaPo从岩盐结构(B1结构)到氯化铯结构(B2结构)的相变以及B1结构CaPo高压下的弹性性质以及热力学性质等.通过等焓原理发现B1→B2的相变压力为22.8GPa. 同时计算了B1结构CaPo高压下的弹性常数以及剪切模量、杨氏模量等相关弹性参数,结果发现当压力超过20GPa时,B1结构CaPo开始不稳定了,这和等焓原理所得结果相符合. 最后通过Debye模型成功获取了B1结构C 关键词： 相变 弹性性质 热力学性质 CaPo

Elastic and thermodynamic properties of CaPo under pressure via first-principles calculations

We investigate the phase transition pressure, elastic and thermodynamic properties of CaPo by the first-principles plane wave pseudo-potential method in the framework of density functional theory. By the isoenthalpy principle, the phase transition pressure from B1 structure to B2 structure is found to be about 22.8GPa. From the high pressure elastic constants obtained, we find that the B1 structure CaPo is unstable when the applied pressure is larger than 20 GPa, which is in good agreement with the results from the isoenthalpy principle. Moreover, the thermodynamic properties of pressure and temperature of B1 structure CaPo(including specific heat capacity, the Debye temperature, thermal expansion and Grüneisen parameter) are also successfully obtained.