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