GPAW Water Basic

from ase import Atoms
from ase.optimize import QuasiNewton
from gpaw import GPAW

system = Atoms('OH2', positions=[[0.0, 0.0, 0.0],
                                 [0.0, 0.0, 1.0],
                                 [0.0, 1.0, 0.0]])

system.set_cell((6.0, 6.0, 6.0))
system.center()

calc = GPAW()
system.set_calculator(calc)

opt = QuasiNewton(system, trajectory='water.gpaw.traj')

opt.run(fmax=0.05)