Elastic Tensors

Let’s do something more interesting that normally takes quite a bit of work in DFT: calculating an elastic constant! Elastic properties are important to understand how strong or easy to deform a material is, or how a material might change if compressed or expanded in specific directions (i.e. the Poisson ratio!).

We don’t have to change much code from above, we just use a built-in recipe to calculate the elastic tensor from quacc. This recipe

1. (optionally) Relaxes the unit cell using the MLIP

2. Generates a number of deformed unit cells by applying strains

3. For each deformation, a relaxation using the MLIP and (optionally) a single point calculation is run

4. Finally, all of the above calculations are used to calculate the elastic properties of the material

For more documentation, see the quacc docs for quacc.recipes.mlp.elastic_tensor_flow

from ase.build import bulk
from quacc.recipes.mlp.elastic import elastic_tensor_flow

# Make an Atoms object of a bulk Cu structure
atoms = bulk("Cu")

# Run an elastic property calculation with our favorite MLP potential
result = elastic_tensor_flow(
    atoms,
    job_params={
        "all": dict(
            method="fairchem",
            model_name="EquiformerV2-31M-OMAT24-MP-sAlex",
            local_cache="./fairchem_checkpoint_cache/",
        ),
    },
)

result["elasticity_doc"].bulk_modulus

Congratulations, you ran your first elastic tensor calculation!