Cij: A Python package for quasiharmonic thermoelasticity

The Wu-Wenzcovitch semi-analytical method (SAM-Cij) [1] provides a concise and predictive formalism for thermoelasticity of crystalline materials at high pressures and temperatures (high-PT). In conjunction with ab-initiocalculations to compute static elasticity and phonons, this approach has been successfully applied to predict high-PT elastic properties of many mantle minerals with different symmetries from cubic (e.g., grossular) to monoclinic (e.g., diopside) systems [2]. Thermoelastic properties obtained with this method have played a profound role in understanding the 1-D composition and structure of the deep Earth and the origin of seismic heterogeneities in the local regions.

Here we introduce the Cij package, a Python implementation of the SAM-Cij method. With this package, a calculation run can be initiated from a single command and is fully-configurable from an individual settings file. This feature allows thermoelasticity calculations to be easily integrated as a component of a high-throughput workflow. In addition to the command-line interface, this code also provides intuitive Python APIs for calculation and plotting.

Research supported by DOE grant DESC0019759.

[1] Z. Wu and R. M. Wentzcovitch, Phys. Rev. B. 83, 184115 (2011).

[2] F. Zou, Z. Wu, W. Wang, and R. M. Wentzcovitch, J. Geophys. Res. 123, (2018).