def vasp_vol_relax():
Al = bulk('Al', 'fcc', a=4.5, cubic=True)
calc = Vasp(xc='LDA',
isif=7,
nsw=5,
ibrion=1,
ediffg=-1e-3,
lwave=False,
lcharg=False)
calc.calculate(Al)
# Explicitly parse atomic position output file from Vasp
CONTCAR_Al = io.read('CONTCAR', format='vasp')
print('Stress after relaxation:\n', calc.read_stress())
print('Al cell post relaxation from calc:\n', calc.get_atoms().get_cell())
print('Al cell post relaxation from atoms:\n', Al.get_cell())
print('Al cell post relaxation from CONTCAR:\n', CONTCAR_Al.get_cell())
# All the cells should be the same.
assert (calc.get_atoms().get_cell() == CONTCAR_Al.get_cell()).all()
assert (Al.get_cell() == CONTCAR_Al.get_cell()).all()
return Al
def ase_vol_relax():
Al = bulk('Al', 'fcc', a=4.5, cubic=True)
calc = Vasp(xc='LDA')
Al.set_calculator(calc)
from ase.constraints import StrainFilter
sf = StrainFilter(Al)
qn = QuasiNewton(sf, logfile='relaxation.log')
qn.run(fmax=0.1, steps=5)
print('Stress:\n', calc.read_stress())
print('Al post ASE volume relaxation\n', calc.get_atoms().get_cell())
return Al