calc_opt = EMT() calc_sp = calc_opt # # ------------------------ bulk --------------------------- # if alloy: bulk = make_bulk(element1, element2=element2, comp1=comp1, repeat=repeat_bulk) else: bulk = make_bulk(element, repeat=repeat_bulk) ## lattice optimization lattice, a0 = lattice_info_guess(bulk) # optimize_lattice_constant(bulk, lattice=lattice, a0=a0, xc=xc, encut=encut, ediff=ediff, ediffg=ediff*0.1, npar=npar, nsim=nsim) bulk.set_calculator(calc_bulk_sp) e_bulk = bulk.get_potential_energy() e_form = 0.0 if alloy and calc_formation_energy: nat = 0 e_bulk_component = 0.0 for ielem in [element1, element2]: tmpbulk = make_bulk(ielem, repeat=2) optimize_lattice_constant(tmpbulk, lattice=lattice, a0=a0, xc=xc, encut=encut, ediff=ediff, ediffg=ediff, npar=npar, nsim=nsim) # # bulk energy for formation energy --- same with alloy surface calculator # # single point
from ase.build import bulk
from gpaw import GPAW, PW, FermiDirac
calc = GPAW(mode=PW(600),
xc='PBE',
occupations=FermiDirac(0.01),
kpts=(32, 32, 16),
symmetry='off',
parallel={
'band': 1,
'domain': 1
},
txt='gs_Co.txt')
bulk = bulk('Co', 'hcp')
bulk.set_initial_magnetic_moments([1.0, 1.0])
bulk.set_calculator(calc)
bulk.get_potential_energy()
calc.write('gs_Co.gpw', mode='all')
def optimize_lattice_constant(bulk,
lattice="fcc",
a0=4.0,
xc="PBEsol",
encut=400,
ediff=1.0e-5,
ediffg=1.0e-6,
npar=1,
nsim=1):
"""
function to do bulk optimization
"""
from ase import Atoms
from ase.calculators.vasp import Vasp
import os, shutil
#
# directry things
#
cudir = os.getcwd()
workdir = os.path.join(cudir, "lattice_opt")
os.makedirs(workdir)
os.chdir(workdir)
os.system("mkdir work_bulk")
#
# compuational condition for Vasp
#
prec = "normal"
potim = 0.1
nelmin = 5
kpts = [3, 3, 3]
gamma = True
nsw = 200
isif = 6 # or 6---freezing ions
xc = xc.lower()
if xc == "pbe" or xc == "pbesol" or xc == "rpbe":
pp = "pbe"
elif xc == "pw91":
pp = "pw91"
elif xc == "lda":
pp = "lda"
else:
print("xc error")
calc = Vasp(prec=prec,
xc=xc,
pp=pp,
ispin=1,
ismear=1,
sigma=0.2,
isif=isif,
nelmin=nelmin,
encut=encut,
ibrion=2,
nsw=nsw,
potim=potim,
ediff=ediff,
ediffg=ediffg,
kpts=kpts,
gamma=gamma,
isym=0,
npar=npar,
nsim=nsim,
lreal=False)
bulk.set_calculator(calc)
bulk.get_potential_energy()
cell = bulk.cell # optimized cell size
os.chdir(cudir)
shutil.rmtree(workdir)