def calc_me(atoms, nbands):
"""Do the calculation."""
molecule_name = atoms.get_chemical_formula()
atoms.set_initial_magnetic_moments([-1.0, 1.0])
fname = '.'.join([molecule_name, 'PBE-SIN'])
calc = GPAW(h=0.25,
xc='PBE',
eigensolver=CG(niter=5),
nbands=nbands,
txt=fname + '.log',
occupations=FermiDirac(0.0, fixmagmom=True),
convergence={
'energy': 0.005,
'bands': nbands,
'eigenstates': 1e-4,
'density': 1e-3
})
atoms.set_calculator(calc)
try:
atoms.get_potential_energy()
except KohnShamConvergenceError:
pass
if calc.scf.converged:
for calcp in calc_parms:
calc.set(**calcp)
try:
calc.calculate(system_changes=[])
except KohnShamConvergenceError:
break
if calc.scf.converged:
calc.write(fname + '.gpw', mode='all')
atoms.set_calculator(calc)
atoms.get_potential_energy()
# Get the valence band maximum
efermi = calc.get_fermi_level()
Nk = len(calc.get_ibz_k_points())
Ns = calc.get_number_of_spins()
eigval = np.array([[calc.get_eigenvalues(kpt=k, spin=s) for k in range(Nk)]
for s in range(Ns)])
evbm = np.max(eigval[eigval < efermi])
# Next, a band structure calculation
calc.set(
nbands=nbnd, # 4 occupied and 4 unoccupied bands
fixdensity=True,
eigensolver=CG(niter=5),
symmetry='off',
kpts={
'path': spath,
'npoints': 50
},
convergence={'bands': 'all'},
)
calc.get_potential_energy()
bs_gpaw = calc.band_structure()
#bs_gpaw.reference = evbm
bs_gpaw_reference = evbm
bs_gpaw.plot(filename='bs_gpaw_data.png',
show=False,
emax=evbm + 5.,
# Fraction of Tw
lambda_coeff = 1.0
name = 'lambda_{0}'.format(lambda_coeff)
filename = 'atoms_' + name + '.dat'
f = paropen(filename, 'w')
elements = ['N']
for symbol in elements:
mixer = Mixer()
eigensolver = CG(tw_coeff=lambda_coeff)
poissonsolver = PoissonSolver()
molecule = Atoms(symbol, positions=[(c, c, c)], cell=(a, a, a))
calc = GPAW(h=h,
xc=xcname,
maxiter=240,
eigensolver=eigensolver,
mixer=mixer,
setups=name,
poissonsolver=poissonsolver)
molecule.set_calculator(calc)
E = molecule.get_total_energy()
