def test_partial_bondorder(verbose=False):
"""Test setup of a molecule which activates partial bond order code."""
from openeye import oechem
mol = oechem.OEMol()
from openeye import oeiupac
oeiupac.OEParseIUPACName(mol, 'benzene')
positions = positions_from_oemol(mol)
oechem.OETriposAtomNames(mol)
topology = generateTopologyFromOEMol(mol)
# Load forcefield from above
ffxml = StringIO(ffxml_contents)
ff = ForceField(ffxml)
# Set up once using AM1BCC charges
system = ff.createSystem(topology, [mol],
chargeMethod='OECharges_AM1BCCSym',
verbose=verbose)
# Check that energy is what it ought to be -- the partial bond order
# for benzene makes the energy a bit higher than it would be without it
energy = get_energy(system, positions)
if energy < 7.50 or energy > 7.60:
raise Exception(
"Partial bond order code seems to have issues, as energy for benzene is outside of tolerance in tests."
)
# Set up once also without asking for charges
system = ff.createSystem(topology, [mol], verbose=verbose)
energy = get_energy(system, positions)
# Energy is lower with user supplied charges (which in this case are zero)
if energy < 4.00 or energy > 6.0:
raise Exception(
"Partial bond order code seems to have issues when run with user-provided charges, as energy for benzene is out of tolerance in tests."
)
def test_parameter_completeness_check(self):
"""Test that proper exceptions are raised if a force field fails to assign parameters to valence terms in a molecule."""
from openeye import oechem
mol = oechem.OEMol()
oechem.OEParseSmiles(mol, 'CCC')
oechem.OEAddExplicitHydrogens(mol)
oechem.OETriposAtomNames(mol)
ff = ForceField(get_data_filename('forcefield/Frosst_AlkEtOH.ffxml'))
topology = generateTopologyFromOEMol(mol)
# Test nonbonded error checking by wiping out required LJ parameter
params = ff.getParameter(paramID='n0001')
params['smirks'] = '[#136:1]'
ff.setParameter(paramID='n0001', params=params)
ff.setParameter(paramID='n0002', params=params)
with self.assertRaises(Exception):
system = ff.createSystem(topology, [mol])
ff = ForceField(get_data_filename('forcefield/Frosst_AlkEtOH.ffxml'))
# Test bond error checking by wiping out a required bond parameter
params = ff.getParameter(paramID='b0001')
params['smirks'] = '[#136:1]~[*:2]'
ff.setParameter(paramID='b0001', params=params)
with self.assertRaises(Exception):
system = ff.createSystem(topology, [mol])
ff = ForceField(get_data_filename('forcefield/Frosst_AlkEtOH.ffxml'))
# Test angle error checking by wiping out a required angle parameter
params = ff.getParameter(paramID='a0001')
params['smirks'] = '[#136:1]~[*:2]~[*:3]'
ff.setParameter(paramID='a0001', params=params)
with self.assertRaises(Exception):
system = ff.createSystem(topology, [mol])
ff = ForceField(get_data_filename('forcefield/Frosst_AlkEtOH.ffxml'))
# Test torsion error checking by wiping out a required torsion parameter
params = ff.getParameter(paramID='t0001')
params['smirks'] = '[#136:1]~[*:2]~[*:3]~[*:4]'
ff.setParameter(paramID='t0001', params=params)
ff.setParameter(paramID='t0004', params=params)
with self.assertRaises(Exception):
system = ff.createSystem(topology, [mol])
ff = ForceField(get_data_filename('forcefield/Frosst_AlkEtOH.ffxml'))
def test_gromacs_roundtrip():
"""Save a System (a mixture) to GROMACS, read back in, verify yields same energy and force terms."""
forcefield = ForceField(
get_data_filename('forcefield/Frosst_AlkEtOH.ffxml'))
filename = get_data_filename(
os.path.join('systems', 'packmol_boxes',
'cyclohexane_ethanol_0.4_0.6.pdb'))
from simtk.openmm.app import PDBFile
pdbfile = PDBFile(filename)
mol2files = [
get_data_filename(os.path.join('systems', 'monomers', 'ethanol.mol2')),
get_data_filename(
os.path.join('systems', 'monomers', 'cyclohexane.mol2'))
]
flavor = oechem.OEIFlavor_Generic_Default | oechem.OEIFlavor_MOL2_Default | oechem.OEIFlavor_MOL2_Forcefield
mols = []
mol = oechem.OEMol()
for mol2file in mol2files:
ifs = oechem.oemolistream(mol2file)
ifs.SetFlavor(oechem.OEFormat_MOL2, flavor)
mol = oechem.OEGraphMol()
while oechem.OEReadMolecule(ifs, mol):
oechem.OETriposAtomNames(mol)
mols.append(oechem.OEGraphMol(mol))
# setup system
system = forcefield.createSystem(pdbfile.topology, mols)
# Create ParmEd structure, save to AMBER
a, topfile = tempfile.mkstemp(suffix='.top')
a, grofile = tempfile.mkstemp(suffix='.gro')
save_system_to_gromacs(pdbfile.topology, system, pdbfile.positions,
topfile, grofile)
# Read back in and cross-check energies
top = parmed.load_file(topfile)
gro = parmed.load_file(grofile)
gromacssys = top.createSystem(nonbondedMethod=app.NoCutoff,
constraints=None,
implicitSolvent=None)
groups0, groups1, energy0, energy1 = compare_system_energies(
pdbfile.topology,
pdbfile.topology,
gromacssys,
system,
pdbfile.positions,
verbose=False)
# Remove temp files
os.remove(topfile)
os.remove(grofile)
def test_change_parameters(verbose=False):
"""Test modification of forcefield parameters."""
from openeye import oechem
# Load simple OEMol
ifs = oechem.oemolistream(
get_data_filename('molecules/AlkEthOH_c100.mol2'))
mol = oechem.OEMol()
flavor = oechem.OEIFlavor_Generic_Default | oechem.OEIFlavor_MOL2_Default | oechem.OEIFlavor_MOL2_Forcefield
ifs.SetFlavor(oechem.OEFormat_MOL2, flavor)
oechem.OEReadMolecule(ifs, mol)
oechem.OETriposAtomNames(mol)
# Load forcefield file
ffxml = get_data_filename('forcefield/Frosst_AlkEtOH.ffxml')
ff = ForceField(ffxml)
from smarty.forcefield import generateTopologyFromOEMol
topology = generateTopologyFromOEMol(mol)
# Create initial system
system = ff.createSystem(topology, [mol], verbose=verbose)
# Get initial energy before parameter modification
positions = positions_from_oemol(mol)
old_energy = get_energy(system, positions)
# Get params for an angle
params = ff.getParameter(smirks='[a,A:1]-[#6X4:2]-[a,A:3]')
# Modify params
params['k'] = '0.0'
ff.setParameter(params, smirks='[a,A:1]-[#6X4:2]-[a,A:3]')
# Write params
ff.writeFile(tempfile.TemporaryFile(suffix='.ffxml'))
# Make sure params changed energy! (Test whether they get rebuilt on system creation)
system = ff.createSystem(topology, [mol], verbose=verbose)
energy = get_energy(system, positions)
if verbose:
print("New energy/old energy:", energy, old_energy)
if np.abs(energy - old_energy) < 0.1:
raise Exception("Error: Parameter modification did not change energy.")
def test_change_parameters(verbose=False):
"""Test modification of forcefield parameters."""
from openeye import oechem
# Load simple OEMol
ifs = oechem.oemolistream(get_data_filename('molecules/AlkEthOH_c100.mol2'))
mol = oechem.OEMol()
flavor = oechem.OEIFlavor_Generic_Default | oechem.OEIFlavor_MOL2_Default | oechem.OEIFlavor_MOL2_Forcefield
ifs.SetFlavor( oechem.OEFormat_MOL2, flavor)
oechem.OEReadMolecule(ifs, mol )
oechem.OETriposAtomNames(mol)
# Load forcefield file
ffxml = get_data_filename('forcefield/Frosst_AlkEtOH.ffxml')
ff = ForceField(ffxml)
from smarty.forcefield import generateTopologyFromOEMol
topology = generateTopologyFromOEMol(mol)
# Create initial system
system = ff.createSystem(topology, [mol], verbose=verbose)
# Get initial energy before parameter modification
positions = positions_from_oemol(mol)
old_energy=get_energy(system, positions)
# Get params for an angle
params = ff.getParameter(smirks='[a,A:1]-[#6X4:2]-[a,A:3]')
# Modify params
params['k']='0.0'
ff.setParameter(params, smirks='[a,A:1]-[#6X4:2]-[a,A:3]')
# Write params
ff.writeFile( tempfile.TemporaryFile(suffix='.ffxml') )
# Make sure params changed energy! (Test whether they get rebuilt on system creation)
system=ff.createSystem(topology, [mol], verbose=verbose)
energy=get_energy(system, positions)
if verbose:
print("New energy/old energy:", energy, old_energy)
if np.abs(energy-old_energy)<0.1:
raise Exception("Error: Parameter modification did not change energy.")
def test_component_combination():
"""Test that a system still yields the same energy after building it again out of its components."""
# We've had issues where subsequent instances of a molecule might have zero charges
# Here we'll try to catch this (and also explicitly check the charges) by re-building
# a system out of its components
forcefield = ForceField(
get_data_filename('forcefield/Frosst_AlkEtOH.ffxml'))
filename = get_data_filename(
os.path.join('systems', 'packmol_boxes',
'cyclohexane_ethanol_0.4_0.6.pdb'))
from simtk.openmm.app import PDBFile
pdbfile = PDBFile(filename)
mol2files = [
get_data_filename(os.path.join('systems', 'monomers', 'ethanol.mol2')),
get_data_filename(
os.path.join('systems', 'monomers', 'cyclohexane.mol2'))
]
flavor = oechem.OEIFlavor_Generic_Default | oechem.OEIFlavor_MOL2_Default | oechem.OEIFlavor_MOL2_Forcefield
mols = []
mol = oechem.OEMol()
for mol2file in mol2files:
ifs = oechem.oemolistream(mol2file)
ifs.SetFlavor(oechem.OEFormat_MOL2, flavor)
mol = oechem.OEGraphMol()
while oechem.OEReadMolecule(ifs, mol):
oechem.OETriposAtomNames(mol)
mols.append(oechem.OEGraphMol(mol))
# setup system
system = forcefield.createSystem(pdbfile.topology,
mols,
chargeMethod='OECharges_AM1BCCSym')
# Make parmed structure
structure = parmed.openmm.topsystem.load_topology(pdbfile.topology, system,
pdbfile.positions)
# Split the system, then re-compose it out of its components
tmp = structure.split()
strs, nums = [], []
for s, n in tmp:
strs.append(s)
nums.append(n)
nums = [len(n) for n in nums]
# Re-compose system from components
new_structure = strs[0] * nums[0]
for idx in range(1, len(nums)):
new_structure += strs[idx] * nums[idx]
# Swap in coordinates again
new_structure.positions = structure.positions
# Create System
newsys = new_structure.createSystem(nonbondedMethod=app.NoCutoff,
constraints=None,
implicitSolvent=None)
# Cross check energies
groups0, groups1, energy0, energy1 = compare_system_energies(
pdbfile.topology,
pdbfile.topology,
system,
newsys,
pdbfile.positions,
verbose=False)
# Also check that that the number of components is equal to the number I expect
if not len(nums) == 2:
print("Error: Test system has incorrect number of components.")
raise Exception(
'Incorrect number of components in cyclohexane/ethanol test system.'
)
# Also check that none of residues have zero charge
for resnr in range(len(structure.residues)):
abscharges = [
abs(structure.residues[resnr].atoms[idx].charge)
for idx in range(len(structure.residues[resnr].atoms))
]
if sum(abscharges) == 0:
raise Exception(
'Error: Residue %s in cyclohexane-ethanol test system has a charge of zero, which is incorrect.'
% resnr)
