ElasT: A toolkit for thermoelastic calculations

A toolkit that simplifies the calculation of solid-state elastic properties at finite temperatures to a one-shot task is developed. We report the improvement and automation of the stress-strain method, which relies on the averaged stresses from ab initio or classical calculations. Stresses obtained from strained crystal lattices at zero and finite temperatures can be directly extracted to fit the strain-stress relationship and get the elastic constants. Furthermore, the finite-temperature elastic constants can also be obtained by solving a system of overdetermined linear equations directly under constant pressure dynamics (NPT, NPH, etc.) within the stress-strain method, which does not require the equilibrated lattice as a prior condition. It is shown that the elastic constants converge quickly in constant pressure dynamics. This approach proves to be robust and can significantly reduce computational cost.

本研究开发了一款工具包，可将有限温度下固态弹性性质的计算简化为单步（one-shot）任务。本工作报道了应力-应变方法的改进与自动化实现，该方法依赖于从头算（ab initio）或经典模拟所得的平均应力。可直接提取零温与有限温度下应变晶格的应力数据，以拟合应变-应力关系并求解弹性常数。此外，在应力-应变方法框架下，亦可直接通过恒压动力学（NPT、NPH等）求解超定线性方程组，以获取有限温度弹性常数，该过程无需以平衡晶格作为先验条件。研究表明，弹性常数在恒压动力学过程中收敛速度较快。该方法具备良好的鲁棒性，且可显著降低计算成本。