Elastic constants and base functions¶

For bulk Si:

import mechelastic
mechelastic.calculate_elastic(code="vasp", dim="3D", infile="OUTCAR-Si_bulk")

For 2D graphene:

import mechelastic
mechelastic.calculate_elastic(code="vasp", dim="2D", infile="OUTCAR-graphene")

For 2D BN:

import mechelastic
mechelastic.calculate_elastic(code="vasp", dim="2D", infile="OUTCAR-BN_mono")

To provide a crystal type (required for the stability test) manualy, the crystal flag can be used. If not provided, MechElatic will determind the crystal symmetry using spglib. The stability test is currently only required for 3D systems:
```
import mechelastic
mechelastic.calculate_elastic(code="vasp", dim="3D", infile="OUTCAR-Si_bulk", crystal="cubic")
```

To run elastic constants calculation for Abinit:

import mechelastic
mechelastic.calculate_elastic(code="abinit", infile="abinit.out", anaddbfile="abinit2.out")

mechelastic.calculate_elastic() calculates the complete set of elastic properties. However, if one wishes to call particular methods that can be also done through the library mode. For example, given a matrix and a crystaltype, the stability can be determined:
```
import mechelastic

parserclass = mechelastic.parsers.VaspOutcar()
elastic_tensor = parserclass.elastic_tensor
crystaltype = "cubic"
mechelastic.tests.stability.stability_test(elastic_tensor, crystaltype)
```

To determine the crystal symmetry:

import mechelastic

parserclass = mechelastic.parsers.VaspOutcar()
elastic_tensor = parserclass.elastic_tensor
cell = parserclass.structure.spglib_cell
mechelastic.utils.crystalutils.crystal_select(elastic_tensor, cell)