def automatic_gamma_density(self,structure, kppa):
"""
Returns an automatic Kpoint object based on a structure and a kpoint
density. Uses Gamma centered meshes always. For GW.
"""
latt = structure.lattice
ngrid = kppa / len(structure.atoms)
lengths = np.linalg.norm(latt,axis=1)
is_2d = is_2d_structure(structure)
if type(is_2d) is tuple:
print('This structure will be treated as a two dimensional structure here',
'so the mesh of one direction will be set to 1 or 2')
vac_idx = is_2d[1]
atom_idx = np.setdiff1d(range(3),vac_idx)
mult = (ngrid * lengths[atom_idx[0]] * lengths[atom_idx[1]]) ** (1 / 2)
num_div = np.zeros((3,))
num_div[atom_idx[0]] = int(math.floor(max(mult / lengths[atom_idx[0]], 1)))
num_div[atom_idx[1]] = int(math.floor(max(mult / lengths[atom_idx[1]], 1)))
num_div[vac_idx] = 1
num_div = num_div.astype(int).tolist()
elif not is_2d :
mult = (ngrid * lengths[0] * lengths[1] * lengths[2]) ** (1 / 3)
num_div = [int(math.floor(max(mult / l, 1))) for l in lengths]
# ensure that numDiv[i] > 0
num_div = [i if i > 0 else 1 for i in num_div]
# VASP documentation recommends to use even grids for n <= 8 and odd
# grids for n > 8.
# num_div = [i + i % 2 if i <= 8 else i - i % 2 + 1 for i in num_div]
style = Kpoints.supported_modes.Gamma
comment = "KPOINTS with grid density = " +"{} / atom".format(kppa)
self.comment = comment
self.num_kpts = 0
self._style = style
self.kpts = [num_div]
self.kpts_shift = [0,0,0]
def automatic_density(self, structure, kppa, force_gamma=False):
"""
Returns an automatic Kpoint object based on a structure and a kpoint
density. Uses Gamma centered meshes for hexagonal cells and
Monkhorst-Pack grids otherwise.
Algorithm:
Uses a simple approach scaling the number of divisions along each
reciprocal lattice vector proportional to its length.
Args:
structure (Structure): Input structure
kppa (int): Grid density
force_gamma (bool): Force a gamma centered mesh (default is to
use gamma only for hexagonal cells or odd meshes)
"""
comment = "grid density = %.0f / atom" % kppa
if math.fabs((math.floor(kppa**(1 / 3) + 0.5))**3 - kppa) < 1:
kppa += kppa * 0.01
ngrid = kppa / len(structure.atoms)
latt = structure.lattice
lengths = np.linalg.norm(latt, axis=1)
is_2d = is_2d_structure(structure)
if type(is_2d) is tuple:
print(
'This structure will be treated as a two dimensional structure here',
'so the mesh of one direction will be set to 1')
vac_idx = is_2d[1]
atom_idx = np.setdiff1d(range(3), vac_idx)
mult = (ngrid * lengths[atom_idx[0]] * lengths[atom_idx[1]])**(1 /
2)
num_div = np.zeros((3, ))
num_div[atom_idx[0]] = int(
math.floor(max(mult / lengths[atom_idx[0]], 1)))
num_div[atom_idx[1]] = int(
math.floor(max(mult / lengths[atom_idx[1]], 1)))
num_div[vac_idx] = 1
num_div = num_div.astype(int).tolist()
elif not is_2d:
mult = (ngrid * lengths[0] * lengths[1] * lengths[2])**(1 / 3)
num_div = [int(math.floor(max(mult / l, 1))) for l in lengths]
spg = structure.get_spacegroup()
if int(spg.split('(')[1].split(')')[0]) in range(168, 195):
is_hexagonal = True # latt.is_hexagonal()
else:
is_hexagonal = False
has_odd = any([i % 2 == 1 for i in num_div])
if has_odd or is_hexagonal or force_gamma:
style = Kpoints.supported_modes.Gamma
else:
style = Kpoints.supported_modes.Monkhorst
self.comment = comment
self.num_kpts = 0
self._style = style
self.kpts = [num_div]
self.kpts_shift = [0, 0, 0]
def __init__(self, poscar='POSCAR'):
self.poscar = poscar
if is_2d_structure(read_vasp(self.poscar)):
self.dimen = 2
else:
self.dimen = 3