# Lattice Parameters

In some codes, optimizing cell parameters on the fly
during geometry relaxations is not available.
For this reason we have compiled
calculated lattice parameters
using multiple different
calculation schemes as a convenience for high-throughput
studies. Every calculation was conducted with
`GPAW`

.

There are two axes to the settings applied here:

- exchange-correlation functional
- basis set mode (finite difference or plane-wave).

Available sets are as follows:

`BULK_PBE_FD`

/`BULK_BEEFVDW_FD`

:`These are parameters using the finite difference scheme and PBE / BEEF-vdW XC functionals. Obtained via fits to an equation of state (https://wiki.fysik.dtu.dk/ase/ase/eos.html) FCC/BCC h = 0.16, kpts = (12,12,12) fit to an SJ EOS HCP h=0.16, kpts = (12,12,6) fit to a Birch-Murnaghan EO`

`BULK_PBE_PW`

/`BULK_BEEFVDW_PW`

:`These are parameters are obatined with a plane-wave basis set and using the Exponential Cell Filter to minimize the stress tensor and atomic forces (https://wiki.fysik.dtu.dk/ase/ase/constraints.html#the-expcellfilter-class) FCC/BCC mode=PW(550), kpts = (12,12,12), fmax = 0.05 eV/A HCP mode=PW(550), kpts = (12,12,6), fmax = 0.05 eV/A`

All of these lattice parameters are available within `autocat.data.lattice_parameters`