Malica Cristiano, Corso Andrea Dal
International School for Advanced Studies (SISSA), Via Bonomea 265, 34136 Trieste, Italy.
IOM-CMR 34136 Trieste, Italy.
J Phys Condens Matter. 2020 May 11;32(31). doi: 10.1088/1361-648X/ab8426.
We presentcalculations of the quasi-harmonic temperature dependent elastic constants. The isothermal elastic constants are calculated at each temperature as second derivatives of the Helmholtz free energy with respect to strain and corrected for finite pressure effects. This calculation is repeated for a grid of geometries and the results interpolated at the minimum of the Helmholtz free energy. The results are compared with the quasi-static elastic constants. Thermodynamic relationships are used to derive the adiabatic elastic constants that are compared with the experimental measurements. These approaches are implemented for cubic solids in thethermo_pwcode and are validated by applications to silicon, aluminum, and silver.
我们给出了准谐温度相关弹性常数的计算结果。等温弹性常数是在每个温度下作为亥姆霍兹自由能关于应变的二阶导数来计算的，并针对有限压力效应进行了修正。对一系列几何结构重复此计算，并在亥姆霍兹自由能的最小值处对结果进行插值。将结果与准静态弹性常数进行比较。利用热力学关系推导出绝热弹性常数，并与实验测量值进行比较。这些方法在thermo_pwcode中针对立方晶体实现，并通过应用于硅、铝和银进行了验证。
