Relaxation of Structure

Perform the structure relaxation is also easy with ASE. This is one example to relax the force of given structure:

import os
import numpy as np
from ase.calculators.interface import Calculator
from ase.lattice.cubic import FaceCenteredCubic
from ase.optimize import BFGS, LBFGS, FIRE
from ase.optimize.sciopt import SciPyFminBFGS, SciPyFminCG
from ase.constraints import StrainFilter, UnitCellFilter
from ase.io.trajectory import Trajectory
from ase import units
import ase.io

from dftpy.config import DefaultOption, OptionFormat
from dftpy.interface import OptimizeDensityConf
from dftpy.api.api4ase import DFTpyCalculator

############################## initial config ##############################
conf = DefaultOption()
conf['PATH']['pppath'] = os.environ.get('DFTPY_DATA_PATH') 
conf['PP']['Al'] = 'Al_lda.oe01.recpot'
conf['JOB']['calctype'] = 'Energy Force Stress'
conf['KEDF']['kedf'] = 'WT'
conf = OptionFormat(conf)
#-----------------------------------------------------------------------
path = os.environ.get('DFTPY_DATA_PATH') 
atoms = ase.io.read(path+'/'+'fcc.vasp')

calc = DFTpyCalculator(config = conf)
atoms.set_calculator(calc)

trajfile = 'opt.traj'

af = atoms

If we want to optimize the stress, just add the StrainFilter :

af = StrainFilter(atoms)

We also can optimize the force and stress at same time, just add the UnitCellFilter :

af = UnitCellFilter(atoms)

The output opt.traj can convert to other format via ASE:

traj = Trajectory(trajfile)
ase.io.write('opt.vasp', traj[-1], direct = True, long_format=True, vasp5 = True)

For more functions and detailed introduction, can refer to ASE.