cij: A Python code for quasiharmonic thermoelasticity

TL;DR

The cij Python package implements the Wu-Wentzcovitch semi-analytical method for calculating the thermoelastic tensor of crystalline materials, facilitating high-throughput and accessible high-pressure and high-temperature studies.

Contribution

It provides an easy-to-use, configurable Python tool for SAM-based thermoelasticity calculations applicable to any crystalline system.

Findings

Successfully applied to diopside, akimotoite, and bridgmanite.

Enables high-throughput calculations on personal computers.

Facilitates insights into Earth's mantle composition.

Abstract

The Wu-Wentzcovitch semi-analytical method (SAM) is a concise and predictive formalism to calculate the high-pressure and high-temperature (high-PT) thermoelastic tensor (Cij) of crystalline materials. This method has been successfully applied to materials across different crystal systems in conjunction with ab initio calculations of static elastic coefficients and phonon frequencies. Such results have offered first-hand insights into the composition and structure of the Earth's mantle. Here we introduce the cij package, a Python implementation of the SAM-Cij formalism. It enables a thermoelasticity calculation to be initiated from a single command and fully configurable from a calculation settings file to work with solids within any crystalline system. These features allow SAM-Cij calculations to work on a personal computer and to be easily integrated as a part of high-throughput workflows. Here we show the performance of this code for three minerals from different crystal systems at their relevant PTs: diopside (monoclinic), akimotoite (trigonal), and bridgmanite (orthorhombic).