from vasp import Vasp
from ase import Atom, Atoms
bond_lengths = [1.05, 1.1, 1.15, 1.2, 1.25]
energies = []
for d in bond_lengths: # possible bond lengths
co = Atoms([Atom('C', [0, 0, 0]), Atom('O', [d, 0, 0])], cell=(6, 6, 6))
calc = Vasp(
'molecules/co-{0}'.format(d), # output dir
xc='PBE',
nbands=6,
encut=350,
ismear=1,
sigma=0.01,
atoms=co)
energies.append(co.get_potential_energy())
print('d = {0:1.2f} ang'.format(d))
print('energy = {0:1.3f} eV'.format(energies[-1] or 0))
print('forces = (eV/ang)\n {0}'.format(co.get_forces()))
print('') # blank line
if None in energies:
calc.abort()
else:
import matplotlib.pyplot as plt
plt.plot(bond_lengths, energies, 'bo-')
plt.xlabel(r'Bond length ($\AA$)')
plt.ylabel('Total energy (eV)')
plt.savefig('images/co-bondlengths.png')
from ase.lattice.surface import fcc111
from vasp import Vasp
slab = fcc111('Al', size=(1, 1, 4), vacuum=10.0)
calc = Vasp('surfaces/Al-bandstructure',
xc='PBE',
encut=300,
kpts=[6, 6, 6],
lcharg=True, # you need the charge density
lwave=True, # and wavecar for the restart
atoms=slab)
n, bands, p = calc.get_bandstructure(kpts_path=[(r'$\Gamma$', [0, 0, 0]),
('$K1$', [0.5, 0.0, 0.0]),
('$K1$', [0.5, 0.0, 0.0]),
('$K2$', [0.5, 0.5, 0.0]),
('$K2$', [0.5, 0.5, 0.0]),
(r'$\Gamma$', [0, 0, 0]),
(r'$\Gamma$', [0, 0, 0]),
('$K3$', [0.0, 0.0, 1.0])],
kpts_nintersections=10)
if p is None: calc.abort()
p.savefig('images/Al-slab-bandstructure.png')
from vasp import Vasp
from ase.lattice.cubic import BodyCenteredCubic
atoms = BodyCenteredCubic(directions=[[1, 0, 0],
[0, 1, 0],
[0, 0, 1]],
size=(1, 1, 1),
symbol='Fe')
NUPDOWNS = [0.0, 2.0, 4.0, 5.0, 6.0, 8.0]
energies = []
for B in NUPDOWNS:
calc = Vasp('bulk/Fe-bcc-fixedmagmom-{0:1.2f}'.format(B),
xc='PBE',
encut=300,
kpts=[4, 4, 4],
ispin=2,
nupdown=B,
atoms=atoms)
energies.append(atoms.get_potential_energy())
if None in energies:
calc.abort()
import matplotlib.pyplot as plt
plt.plot(NUPDOWNS, energies)
plt.xlabel('Total Magnetic Moment')
plt.ylabel('Energy (eV)')
plt.savefig('images/Fe-fixedmagmom.png')
cell=(10, 10, 10))
calc = Vasp('molecules/O-sp-triplet-{0}'.format(encut),
xc='PBE',
encut=encut,
ismear=0,
ispin=2,
atoms=atoms)
E_O = atoms.get_potential_energy()
# now relaxed O2 dimer
atoms = Atoms([Atom('O', [5, 5, 5], magmom=1),
Atom('O', [6.22, 5, 5], magmom=1)],
cell=(10, 10, 10))
calc = Vasp('molecules/O2-sp-triplet-{0}'.format(encut),
xc='PBE',
encut=encut,
ismear=0,
ispin=2, # turn spin-polarization on
ibrion=2, # this turns relaxation on
nsw=10,
atoms=atoms)
E_O2 = atoms.get_potential_energy()
if None not in (E_O, E_O2):
d = 2*E_O - E_O2
D.append(d)
print('O2 -> 2O encut = {0} D = {1:1.3f} eV'.format(encut, d))
if not D or None in D: calc.abort()
import matplotlib.pyplot as plt
plt.plot(encuts, D)
plt.xlabel('ENCUT (eV)')
plt.ylabel('O$_2$ dissociation energy (eV)')
plt.savefig('images/O2-dissociation-convergence.png')
