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import subprocess
from ase import Atoms
from ase.calculators.amber import Amber
def test_amber(factories):
"""Test that amber calculator works.
This is conditional on the existence of the $AMBERHOME/bin/sander
executable.
"""
factories.require('amber')
with open('mm.in', 'w') as outfile:
outfile.write("""\
zero step md to get energy and force
&cntrl
imin=0, nstlim=0, ntx=1 !0 step md
cut=100, ntb=0, !non-periodic
ntpr=1,ntwf=1,ntwe=1,ntwx=1 ! (output frequencies)
&end
END
""")
with open('tleap.in', 'w') as outfile:
outfile.write("""\
source leaprc.protein.ff14SB
source leaprc.gaff
source leaprc.water.tip3p
mol = loadpdb 2h2o.pdb
saveamberparm mol 2h2o.top h2o.inpcrd
quit
""")
subprocess.call('tleap -f tleap.in'.split())
atoms = Atoms('OH2OH2',
[[-0.956, -0.121, 0],
[-1.308, 0.770, 0],
[0.000, 0.000, 0],
[3.903, 0.000, 0],
[4.215, -0.497, -0.759],
[4.215, -0.497, 0.759]])
calc = Amber(amber_exe='sander -O ',
infile='mm.in',
outfile='mm.out',
topologyfile='2h2o.top',
incoordfile='mm.crd')
calc.write_coordinates(atoms, 'mm.crd')
atoms.calc = calc
e = atoms.get_potential_energy()
assert abs(e + 0.046799672) < 5e-3
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