def calculate_bandstructure(self, bs):
""" Returns a BandStructure object with a DFTB band structure.
Assumes that the necessary *-*.skf files have been generated.
bs: ase.dft.band_structure.BandStructure instance with an
additional 'atoms' and 'kpts_scf' attributes. The latter
represents the k-points to be used in the self-consistent
calculation prior to the bandstructure calculation in DFTB.
"""
# Perform a regular DFTB calculation first
# to converge the charges and get the
# reference energy
atoms = bs.atoms.copy()
calc = Dftb(atoms=atoms, kpts=bs.kpts_scf, **self.dftbplus_kwargs)
atoms.set_calculator(calc)
etot = atoms.get_potential_energy()
efermi = calc.get_fermi_level()
if bs.reference_level == 'vbm':
eig = np.array(calc.results['eigenvalues'])
eref = np.max(eig[eig < efermi])
elif bs.reference_level == 'fermi':
eref = efermi
# Now a band structure calculation
kwargs = self.dftbplus_kwargs.copy()
kwargs.update({
'Hamiltonian_MaxSCCIterations': 1,
'Hamiltonian_ReadInitialCharges': 'Yes',
'Hamiltonian_SCCTolerance': 1e6
})
calc = Dftb(atoms=atoms, kpts=bs.path.kpts, **kwargs)
atoms.set_calculator(calc)
etot = atoms.get_potential_energy()
# Update the reference level, k-points,
# and eigenenergies
bs_new = copy.deepcopy(bs)
#bs_new.reference = eref
bs_new_reference = eref
bs_new.kpts = calc.get_ibz_k_points()
#bs_new.energies = []
bs_new_energies = []
for s in range(calc.get_number_of_spins()):
#bs_new.energies.append([calc.get_eigenvalues(kpt=k, spin=s)
bs_new_energies.append([
calc.get_eigenvalues(kpt=k, spin=s)
for k in range(len(bs_new.kpts))
])
#bs_new.energies = np.array(bs_new.energies)
bs_new_energies = np.array(bs_new_energies)
return bs_new
if '17.1' not in version:
msg = 'Band structure properties not present in results.tag for ' + version
raise SkipTest(msg)
# The actual testing starts here
calc = Dftb(label='dftb',
kpts=(3, 3, 3),
Hamiltonian_SCC='Yes',
Hamiltonian_SCCTolerance=1e-5,
Hamiltonian_MaxAngularMomentum_Si='d')
atoms = bulk('Si')
atoms.set_calculator(calc)
atoms.get_potential_energy()
efermi = calc.get_fermi_level()
assert abs(efermi - -2.90086680996455) < 1.
# DOS does not currently work because of
# missing "get_k_point_weights" function
#from ase.dft.dos import DOS
#dos = DOS(calc, width=0.2)
#d = dos.get_dos()
#e = dos.get_energies()
#print(d, e)
calc = Dftb(atoms=atoms,
label='dftb',
kpts={
'path': 'WGXWLG',
'npoints': 50
def test_dftb_bandstructure():
import os
import subprocess
from unittest import SkipTest
from ase.test import require
from ase.test.testsuite import datafiles_directory
from ase.calculators.dftb import Dftb
from ase.build import bulk
require('dftb')
os.environ['DFTB_PREFIX'] = datafiles_directory
# We need to get the DFTB+ version to know
# whether to skip this test or not.
# For this, we need to run DFTB+ and grep
# the version from the output header.
cmd = os.environ['ASE_DFTB_COMMAND'].split()[0]
proc = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE)
lines = ''
for line in proc.stdout:
l = line.decode()
if 'DFTB+' in l and ('version' in l.lower() or 'release' in l.lower()):
version = l[l.index('DFTB+'):]
break
lines += l + '\n'
else:
raise RuntimeError('Could not parse DFTB+ version ' + lines)
if '17.1' not in version:
msg = 'Band structure properties not present in results.tag for ' + version
raise SkipTest(msg)
# The actual testing starts here
calc = Dftb(label='dftb',
kpts=(3, 3, 3),
Hamiltonian_SCC='Yes',
Hamiltonian_SCCTolerance=1e-5,
Hamiltonian_MaxAngularMomentum_Si='d')
atoms = bulk('Si')
atoms.set_calculator(calc)
atoms.get_potential_energy()
efermi = calc.get_fermi_level()
assert abs(efermi - -2.90086680996455) < 1.
# DOS does not currently work because of
# missing "get_k_point_weights" function
#from ase.dft.dos import DOS
#dos = DOS(calc, width=0.2)
#d = dos.get_dos()
#e = dos.get_energies()
#print(d, e)
calc = Dftb(atoms=atoms,
label='dftb',
kpts={
'path': 'WGXWLG',
'npoints': 50
},
Hamiltonian_SCC='Yes',
Hamiltonian_MaxSCCIterations=1,
Hamiltonian_ReadInitialCharges='Yes',
Hamiltonian_MaxAngularMomentum_Si='d')
atoms.set_calculator(calc)
calc.calculate(atoms)
calc.results['fermi_levels'] = [efermi]
calc.band_structure()
