Elastic Tensor Skill

This skill calculates the full elastic tensor ($C_{ij}$) and derived mechanical properties of crystalline materials using Machine Learning Interatomic Potentials (MLIPs). It applies a set of normal and shear strains, computes the resulting stresses, and fits the elastic constants via least-squares regression using MatCalc's ElasticityCalc.

Goal

Calculate the elastic tensor ($C_{ij}$) of a material by applying systematic deformations (normal and shear strains), computing the stress response with an MLIP, and extracting the full Voigt elastic tensor along with:

• Bulk modulus $B$ (Voigt-Reuss-Hill average)
• Shear modulus $G$ (Voigt-Reuss-Hill average)
• Young's modulus $E$
• Poisson's ratio $\nu$

1. Prerequisites

• The appropriate MLIP wrapper must be available (MACEWrapper, MatGLWrapper, or FAIRCHEMWrapper).
• matcalc must be installed in the relevant conda environment.
• A structure file (CIF, POSCAR, or other ASE-readable format). The structure will be relaxed before deformation by default.

2. Choosing a Foundation Potential