Cij: A Python code for thermoelasticity*

The Wu-Wenzcovitch semi-analytical method is a concise and predictive formalism to compute the high pressure and high temperature (high-PT) thermoelastic tensor (SAM-Cij) of crystalline materials. In conjunction with ab-initio calculations to compute static elastic coefficients and phonon frequencies, this method has been successfully applied to materials across different crystal systems. Mineral elastic properties under mantle conditions obtained with this method have provided first-hand insights into the origins of seismic heterogeneities in Earth's mantle. Here, we introduce the Cij package, a Python implementation of the SAM-Cij method. It enables a thermoelasticity calculation to be initiated from a single command and is fully-configurable from an available calculation settings file to work with different materials. These features allow SAM-Cij calculations to be easily integrated as a part of high-throughput workflows. In addition to the command-line interface, this package also provides intuitive Python APIs for analysis and plotting.