def test_cbmc_setters(self, methane_oplsaa):
moveset = mc.MoveSet("gemc", [methane_oplsaa])
with pytest.raises(TypeError, match=r"must be of type int"):
moveset.cbmc_n_insert = 12.2
with pytest.raises(ValueError, match=r"must be greater than zero"):
moveset.cbmc_n_insert = -2
moveset.cbmc_n_insert = 20
assert moveset.cbmc_n_insert == 20
with pytest.raises(TypeError, match=r"must be of type int"):
moveset.cbmc_n_dihed = 12.2
with pytest.raises(ValueError, match=r"must be greater than zero"):
moveset.cbmc_n_dihed = -2
moveset.cbmc_n_dihed = 20
assert moveset.cbmc_n_dihed == 20
with pytest.raises(TypeError, match=r"unyt_array"):
moveset.cbmc_rcut = [3.0 * u.angstrom]
with pytest.raises(TypeError, match=r"unyt_array"):
moveset.cbmc_rcut = 3.0
with pytest.raises(ValueError, match=r"less than zero"):
moveset.cbmc_rcut = [3.0 * u.angstrom, -3.0 * u.angstrom]
with pytest.raises(IterableUnitCoercionError):
moveset.cbmc_rcut = [0.4 * u.nm, 8.0 * u.angstrom]
moveset.cbmc_rcut = 5.0 * u.angstrom
assert len(moveset.cbmc_rcut) == 2
assert moveset.cbmc_rcut[0].to_value("angstrom") == 5.0
assert moveset.cbmc_rcut[1].to_value("angstrom") == 5.0
moveset = mc.MoveSet("nvt", [methane_oplsaa])
moveset.cbmc_rcut = 7.0 * u.angstrom
assert len(moveset.cbmc_rcut) == 1
assert moveset.cbmc_rcut[0].to_value("angstrom") == 7.0
def test_mismatch_boxes(self, methane_oplsaa, box):
with pytest.raises(ValueError, match=r"requires 1 simulation"):
system = mc.System([box, box], [methane_oplsaa],
mols_to_add=[[10], [0]])
moveset = mc.MoveSet("nvt", [methane_oplsaa])
mc.run(system, moveset, 300.0, "equilibration", 500)
with pytest.raises(ValueError, match=r"requires 2 simulation"):
system = mc.System([box], [methane_oplsaa], mols_to_add=[[10]])
moveset = mc.MoveSet("gemc", [methane_oplsaa])
mc.run(system, moveset, 300.0, "equilibration", 500)
def test_corrupt_topologies(self, methane_oplsaa, box):
with pytest.raises(TypeError, match=r"corrupted"):
system = mc.System([box], [methane_oplsaa], mols_to_add=[[10]])
moveset = mc.MoveSet("nvt", [methane_oplsaa])
system._species_topologies = methane_oplsaa
mc.run(system, moveset, 300.0, "equilibration", 500)
with pytest.raises(TypeError, match=r"corrupted"):
system = mc.System([box], [methane_oplsaa], mols_to_add=[[10]])
moveset = mc.MoveSet("nvt", [methane_oplsaa])
system.species_topologies[0] = 1
mc.run(system, moveset, 300.0, "equilibration", 500)
def test_corrupt_natoms(self, methane_oplsaa, box):
with pytest.raises(ValueError, match=r"corrupted"):
system = mc.System([box], [methane_oplsaa], mols_to_add=[[10]])
moveset = mc.MoveSet("nvt", [methane_oplsaa])
system.mols_in_boxes[0][0] = 10
mc.run(system, moveset, 300.0, "equilibration", 500)
def test_ensemble_npt(self, methane_oplsaa):
moveset = mc.MoveSet("npt", [methane_oplsaa])
assert moveset.ensemble == "npt"
assert moveset.prob_translate == 0.33
assert moveset.prob_rotate == 0.33
assert moveset.prob_regrow == 0.335
assert moveset.prob_volume == 0.005
assert moveset.prob_angle == 0.0
assert moveset.prob_dihedral == 0.0
assert moveset.prob_insert == 0.0
assert moveset.prob_swap == 0.0
# Per box attributes
assert len(moveset.max_translate) == 1
assert len(moveset.max_rotate) == 1
assert len(moveset.max_volume) == 1
assert len(moveset.prob_swap_from_box) == 1
assert moveset.prob_swap_from_box[0] == 1.0
assert moveset.max_volume[0] == 500.0 * (u.angstrom ** 3)
# Per species-per-box
assert len(moveset.max_translate[0]) == 1 * u.angstrom
assert len(moveset.max_rotate[0]) == 1 * u.degree
# Per species attributes
assert len(moveset.insertable) == 1
assert len(moveset.prob_swap_species) == 1
assert len(moveset.prob_regrow_species) == 1
# Should be regrow-able but not insertable
assert moveset.prob_regrow_species[0] == 1.0
assert moveset.insertable[0] == False
def test_gcmc_lattice(self, fixed_lattice_trappe, methane_trappe):
moveset = mc.MoveSet("gcmc", [fixed_lattice_trappe, methane_trappe])
assert moveset.ensemble == "gcmc"
assert moveset.prob_translate == pytest.approx(0.8)
assert moveset.prob_rotate == 0.0
assert moveset.prob_regrow == 0.0
assert moveset.prob_volume == 0.0
assert moveset.prob_angle == 0.0
assert moveset.prob_dihedral == 0.0
assert moveset.prob_insert == 0.1
assert moveset.prob_swap == pytest.approx(0.0)
# Per box attributes
assert len(moveset.max_translate) == 1
assert len(moveset.max_rotate) == 1
assert len(moveset.max_volume) == 1
assert len(moveset.prob_swap_from_box) == 1
assert moveset.prob_swap_from_box[0] == 1.0
assert moveset.max_volume[0] == 0.0
# Per species-per-box
assert len(moveset.max_translate[0]) == 2
assert len(moveset.max_rotate[0]) == 2
# Per species attributes
assert len(moveset.insertable) == 2
assert len(moveset.prob_swap_species) == 2
assert len(moveset.prob_regrow_species) == 2
# Lattice should not be insertable or regrow-able
assert moveset.insertable[0] == False
assert moveset.prob_regrow_species[0] == 0.0
# Methane should be insertable and not regrow-able
assert moveset.insertable[1] == True
assert moveset.prob_regrow_species[1] == 0.0
def test_single_site_nvt(self, methane_trappe):
moveset = mc.MoveSet("nvt", [methane_trappe])
assert moveset.ensemble == "nvt"
assert moveset.prob_rotate == 0.0
assert moveset.prob_regrow == 0.0
assert moveset.prob_translate == 1.0
assert moveset.prob_volume == 0.0
assert moveset.prob_angle == 0.0
assert moveset.prob_dihedral == 0.0
assert moveset.prob_insert == 0.0
assert moveset.prob_swap == 0.0
# Per box attributes
assert len(moveset.max_translate) == 1
assert len(moveset.max_rotate) == 1
assert len(moveset.max_volume) == 1
assert len(moveset.prob_swap_from_box) == 1
assert moveset.prob_swap_from_box[0] == 1.0
assert moveset.max_volume[0] == 0.0
# Per species-per-box
assert len(moveset.max_translate[0]) == 1
assert len(moveset.max_rotate[0]) == 1
# Per species attributes
assert len(moveset.insertable) == 1
assert len(moveset.prob_swap_species) == 1
assert len(moveset.prob_regrow_species) == 1
# Should NOT be insertable or regrow-able
assert moveset.insertable[0] == False
assert moveset.prob_regrow_species[0] == 0.0
def test_add_multiple_restricted_insertions(self, methane_oplsaa):
moveset = mc.MoveSet("gcmc", [methane_oplsaa])
moveset.add_restricted_insertions([methane_oplsaa], [["slitpore"]],
[[3 * u.angstrom]])
with pytest.warns(None) as record:
moveset.add_restricted_insertions([methane_oplsaa], [["cylinder"]],
[[3 * u.angstrom]])
def test_restricted_gemc(self, methane_oplsaa, typ, value):
moveset = mc.MoveSet("gemc", [methane_oplsaa])
moveset.add_restricted_insertions([methane_oplsaa], [[None], [typ]],
[[None], [value]])
assert moveset._restricted_type == [[None], [typ]]
assert moveset._restricted_value == [[None], [value]]
def test_invalid_species_list(self, methane_oplsaa):
with pytest.raises(
TypeError,
match=r"species_topologies should "
"be a list of species",
):
moveset = mc.MoveSet("nvt", methane_oplsaa)
def run_nvt(**custom_args):
# Use mBuild to create a methane molecule
methane = mbuild.load("C", smiles=True)
# Create an empty mbuild.Box
box = mbuild.Box(lengths=[3.0, 3.0, 3.0])
# Load force field
oplsaa = foyer.forcefields.load_OPLSAA()
# Use foyer to apply force field to methane
methane_ff = oplsaa.apply(methane)
# Create box and species list
box_list = [box]
species_list = [methane_ff]
# Use Cassandra to insert some initial number of methane molecules
mols_to_add = [[50]]
# Define the System
system = mc.System(box_list, species_list, mols_to_add=mols_to_add)
# Define the MoveSet
moveset = mc.MoveSet("nvt", species_list)
# Run a simulation at 300 K for 10000 MC moves
mc.run(
system=system,
moveset=moveset,
run_type="equilibration",
run_length=10000,
temperature=300.0 * u.K,
**custom_args,
)
def test_ensemble_gcmc(self, methane_oplsaa):
moveset = mc.MoveSet("gcmc", [methane_oplsaa])
assert moveset.ensemble == "gcmc"
assert moveset.prob_translate == 0.25
assert moveset.prob_rotate == 0.25
assert moveset.prob_regrow == 0.30
assert moveset.prob_volume == 0.0
assert moveset.prob_angle == 0.0
assert moveset.prob_dihedral == 0.0
assert moveset.prob_insert == 0.1
assert moveset.prob_swap == 0.0
# Per box attributes
assert len(moveset.max_translate) == 1
assert len(moveset.max_rotate) == 1
assert len(moveset.max_volume) == 1
assert len(moveset.prob_swap_from_box) == 1
assert moveset.prob_swap_from_box[0] == 1.0
assert moveset.max_volume[0] == 0.0 * (u.angstrom ** 3)
# Per species-per-box
assert len(moveset.max_translate[0]) == 1
assert len(moveset.max_rotate[0]) == 1
# Per species attributes
assert len(moveset.insertable) == 1
assert len(moveset.prob_swap_species) == 1
assert len(moveset.prob_regrow_species) == 1
# Should be insertable and regrow-able
assert moveset.insertable[0] == True
assert moveset.prob_regrow_species[0] == 1.0
def test_single_site_gemc(self, methane_trappe):
moveset = mc.MoveSet("gemc", [methane_trappe])
assert moveset.ensemble == "gemc"
assert moveset.prob_rotate == 0.0
assert moveset.prob_regrow == 0.0
assert moveset.prob_translate == pytest.approx(0.895)
assert moveset.prob_volume == 0.005
assert moveset.prob_angle == 0.0
assert moveset.prob_dihedral == 0.0
assert moveset.prob_insert == 0.0
assert moveset.prob_swap == 0.1
# Per box attributes
assert len(moveset.max_translate) == 2
assert len(moveset.max_rotate) == 2
assert len(moveset.max_volume) == 1
assert len(moveset.prob_swap_from_box) == 2
assert moveset.prob_swap_from_box[0] == 0.5
assert moveset.prob_swap_from_box[1] == 0.5
assert moveset.max_volume[0] == 500.0
# Per species-per-box
assert len(moveset.max_translate[0]) == 1
assert len(moveset.max_translate[1]) == 1
assert len(moveset.max_rotate[0]) == 1
assert len(moveset.max_rotate[1]) == 1
# Per species attributes
assert len(moveset.insertable) == 1
assert len(moveset.prob_swap_species) == 1
assert len(moveset.prob_regrow_species) == 1
# Should be insertable and NOT regrow-able
assert moveset.insertable[0] == True
assert moveset.prob_regrow_species[0] == 0.0
def test_restricted_gemc_npt(self, methane_oplsaa):
moveset = mc.MoveSet("gemc_npt", [methane_oplsaa])
moveset.add_restricted_insertions(
[methane_oplsaa],
[[None], ["slitpore"]],
[[None], [3 * u.angstrom]],
)
assert moveset._restricted_type == [[None], ["slitpore"]]
assert moveset._restricted_value == [[None], [3 * u.angstrom]]
def run_gcmc_adsorption(**custom_args):
# Use mbuild to create a zeolite supercell from CIF
lattice = mbuild.lattice.load_cif(get_example_cif_path("TON"))
compound_dict = {
"Si": mbuild.Compound(name="Si"),
"O": mbuild.Compound(name="O"),
}
ton = lattice.populate(compound_dict, 3, 3, 6)
# Create a coarse-grained methane
methane = mbuild.Compound(name="_CH4")
# Load forcefields
trappe_zeo = foyer.Forcefield(get_example_ff_path("trappe_zeo"))
trappe = foyer.forcefields.load_TRAPPE_UA()
# Use foyer to apply forcefields
ton_ff = trappe_zeo.apply(ton)
methane_ff = trappe.apply(methane)
# Create box and species list
box_list = [ton]
species_list = [ton_ff, methane_ff]
# Since we have an occupied box we need to specify
# the number of each species present in the intial config
mols_in_boxes = [[1, 0]]
system = mc.System(box_list, species_list, mols_in_boxes=mols_in_boxes)
moveset = mc.MoveSet("gcmc", species_list)
default_args = {
"chemical_potentials": ["none", -30.0 * (u.kJ / u.mol)],
"rcut_min": 0.5 * u.angstrom,
"vdw_cutoff": 14.0 * u.angstrom,
"charge_cutoff": 14.0 * u.angstrom,
"coord_freq": 100,
"prop_freq": 10,
}
# Combine default/custom args and override default
custom_args = {**default_args, **custom_args}
mc.run(
system=system,
moveset=moveset,
run_type="equilibration",
run_length=10000,
temperature=300.0 * u.K,
**custom_args,
)
def run_cassandra_surf(chem_pot, temp):
# Create box and species list
box_list = [surface]
species_list = [typed_surface,typed_ethane]
# Since we have an occupied box we need to specify
# the number of each species present in the intial config
mols_in_boxes = [[2,0]]
system = mc.System(box_list, species_list, mols_in_boxes=mols_in_boxes)
moveset = mc.MoveSet("gcmc", species_list)
custom_args = {
"run_name": f"surfequil_{chem_pot:.0f}_{temp:.0f}",
"chemical_potentials": ["none",chem_pot*u.Unit('kJ/mol')],
"rcut_min": 0.3980 * 2.5* u.angstrom, #(or 3.0)
"vdw_cutoff": min(box.lengths)/2.1* u.angstrom,
"charge_style": "none",
#"charge_cutoff": 14.0,
"coord_freq": 100,
"prop_freq": 10,
}
mc.run(
system=system,
moveset=moveset,
run_type="equilibration",
run_length= 3600549, # To reach ~1.33 hours
temperature=temp*u.K,
**custom_args
)
# Set max translate and volume for production
moveset.max_translate = [[0* u.angstrom,10.0* u.angstrom]] # angstroms
# Update run_name and restart_name
custom_args["run_name"] = f"surfprod_{chem_pot:.0f}_{temp:.0f}"
custom_args["restart_name"] = f"surfequil_{chem_pot:.0f}_{temp:.0f}"
mc.restart(
system=system,
moveset=moveset,
run_type="production",
run_length= 24097256, # To reach ~6.67 hours, total 8 hrs
temperature=temp*u.K,
**custom_args,
)
def run_gcmc_adsorption(**custom_args):
# Use mbuild to create molecules
lattice = carbon_lattice()
methane = mbuild.load("C", smiles=True)
# Load forcefields
trappe = foyer.forcefields.load_TRAPPE_UA()
oplsaa = foyer.forcefields.load_OPLSAA()
# Use foyer to apply forcefields
typed_lattice = trappe.apply(lattice)
methane_ff = oplsaa.apply(methane)
# Create box and species list
box_list = [lattice]
species_list = [typed_lattice, methane_ff]
# Since we have an occupied box we need to specify
# the number of each species present in the intial config
mols_in_boxes = [[1, 0]]
system = mc.System(box_list, species_list, mols_in_boxes=mols_in_boxes)
moveset = mc.MoveSet("gcmc", species_list)
default_args = {
"chemical_potentials": ["none", -30.0 * (u.kJ / u.mol)],
"rcut_min": 0.5 * u.angstrom,
"vdw_cutoff": 14.0 * u.angstrom,
"charge_cutoff": 14.0 * u.angstrom,
"coord_freq": 100,
"prop_freq": 10,
}
# Combine default/custom args and override default
custom_args = {**default_args, **custom_args}
mc.run(
system=system,
moveset=moveset,
run_type="equilibration",
run_length=10000,
temperature=300.0 * u.K,
**custom_args,
)
def run_nvt_spce(**custom_args):
# If no custom args are passed, assign empty dictionary
#if custom_args is None:
# custom_args = {}
# Load water with SPC/E geometry from mol2 file
molecule = mbuild.load(get_example_mol2_path("spce"))
# Create an empty mbuild.Box
box = mbuild.Box(lengths=[3.0, 3.0, 3.0])
# Load forcefields
spce = foyer.Forcefield(get_example_ff_path("spce"))
# Use foyer to apply forcefields
molecule_ff = spce.apply(molecule)
# Create box and species list
box_list = [box]
species_list = [molecule_ff]
# Use Cassandra to insert some initial number of species
mols_to_add = [[50]]
# Define the system object
system = mc.System(box_list, species_list, mols_to_add=mols_to_add)
# Get the move probabilities
moveset = mc.MoveSet("nvt", species_list)
default_args = {
"angle_style": ["fixed"],
}
# Combine default/custom args and override default
custom_args = {**default_args, **custom_args}
# Run a simulation with at 300 K with 10000 MC moveset
mc.run(
system=system,
moveset=moveset,
run_type="equilibration",
run_length=10000,
temperature=300.0 * u.K,
**custom_args,
)
def run_gcmc_restricted(**custom_args):
# Use mbuild to create molecules
methane = mbuild.load("C", smiles=True)
# Create an empty mbuild.Box
box = mbuild.Box(lengths=[5.0, 5.0, 5.0])
# Load forcefields
oplsaa = foyer.forcefields.load_OPLSAA()
# Use foyer to apply forcefields
methane_ff = oplsaa.apply(methane)
# Create box and species list
box_list = [box]
species_list = [methane_ff]
mols_to_add = [[10]]
system = mc.System(box_list, species_list, mols_to_add=mols_to_add)
moveset = mc.MoveSet("gcmc", species_list)
# Specify restricted insertions
moveset.add_restricted_insertions(
species_list, [["sphere"]], [[20 * u.angstrom]]
)
default_args = {
"chemical_potentials": [-35.0 * (u.kJ / u.mol)],
"prop_freq": 10,
}
# Combine default/custom args and override default
custom_args = {**default_args, **custom_args}
mc.run(
system=system,
moveset=moveset,
run_type="equilibration",
run_length=100,
temperature=300.0 * u.K,
**custom_args,
)
def run_nvt_mbuild(fix_bonds, **custom_args):
dme = mbuild.load("COC", smiles=True)
dee = mbuild.load("CCOCC", smiles=True)
# Create an empty mbuild.Box
box = mbuild.Box(lengths=[3.0, 3.0, 3.0])
# fill box
box = mbuild.fill_box([dme, dee], n_compounds=[10, 10], box=box)
# Load forcefields
ff = foyer.forcefields.load_OPLSAA()
# Use foyer to apply forcefields
dme_ff = ff.apply(dme)
dee_ff = ff.apply(dee)
# Create box and species list
box_list = [box]
species_list = [dme_ff, dee_ff]
# Use Cassandra to insert some initial number of species
mols_in_boxes = [[10, 10]]
# Define the system object
system = mc.System(
box_list,
species_list,
mols_in_boxes=mols_in_boxes,
fix_bonds=fix_bonds,
)
# Get the move probabilities
moveset = mc.MoveSet("nvt", species_list)
# Run a simulation with at 300 K with 10000 MC moves
mc.run(
system=system,
moveset=moveset,
run_type="equilibration",
run_length=100,
temperature=300.0 * u.K,
**custom_args,
)
def run_npt(**custom_args):
# Use mbuild to create molecules
methane = mbuild.load("C", smiles=True)
# Create an empty mbuild.Box
box = mbuild.Box(lengths=[3.0, 3.0, 3.0])
# Load forcefields
oplsaa = foyer.forcefields.load_OPLSAA()
# Use foyer to apply forcefields
methane_ff = oplsaa.apply(methane)
# Create box and species list
box_list = [box]
species_list = [methane_ff]
# Use Cassandra to insert some initial number of species
mols_to_add = [[5]]
# Define the system object
system = mc.System(box_list, species_list, mols_to_add=mols_to_add)
# Get the move probabilities
moveset = mc.MoveSet("npt", species_list)
default_args = {
"pressure": 1.0 * u.bar,
}
# Combine default/custom args and override default
custom_args = {**default_args, **custom_args}
# Run a simulation with at 300 K with 10000 MC moveset
# Note we must define a pressure for an NPT simulation
mc.run(
system=system,
moveset=moveset,
run_type="equilibration",
run_length=10000,
temperature=300.0 * u.K,
**custom_args,
)
# Create a single site methane molecule
methane = mbuild.Compound(name="_CH4")
# Apply the force field
methane_ff = ff.apply(methane)
# Create an empty 3x3x3 nm^3 simulation box
box = mbuild.Box([3., 3., 3.])
# Define the box/species lists
box_list = [box]
species_list = [methane_ff]
# Tell Cassandra to add 100 methane at the start
mols_to_add = [[100]]
# Create the System and MoveSet
system = mc.System(box_list, species_list, mols_to_add=mols_to_add)
moveset = mc.MoveSet("npt", species_list)
# Run the Monte Carlo simulation
mc.run(
system=system,
moveset=moveset,
run_type="equilibration",
run_length=300000,
temperature=240 * u.K,
pressure=10.0 * u.bar,
)
def test_invalid_restricted_type_and_species(self, methane_oplsaa):
moveset = mc.MoveSet("gcmc", [methane_oplsaa])
with pytest.raises(ValueError, match=r"Length of 'species'"):
moveset.add_restricted_insertions(
[methane_oplsaa], [["slitpore", None]], [[1, None]]
)
def test_change_ensemble(self, methane_oplsaa):
moveset = mc.MoveSet("gcmc", [methane_oplsaa])
with pytest.raises(
AttributeError, match=r"Ensemble cannot be changed"
):
moveset.ensemble = "nvt"
def run_gemc(**custom_args):
# Use mbuild to create molecules
methane = mbuild.Compound(name="_CH4")
# Create two empty mbuild.Box
# (vapor = larger, liquid = smaller)
liquid_box = mbuild.Box(lengths=[3.0, 3.0, 3.0])
vapor_box = mbuild.Box(lengths=[4.0, 4.0, 4.0])
# Load forcefields
trappe = foyer.forcefields.load_TRAPPE_UA()
# Use foyer to apply forcefields
typed_methane = trappe.apply(methane)
# Create box and species list
box_list = [liquid_box, vapor_box]
species_list = [typed_methane]
mols_to_add = [[350], [100]]
system = mc.System(box_list, species_list, mols_to_add=mols_to_add)
moveset = mc.MoveSet("gemc", species_list)
moveset.prob_volume = 0.010
moveset.prob_swap = 0.11
thermo_props = [
"energy_total",
"energy_intervdw",
"pressure",
"volume",
"nmols",
"mass_density",
]
default_args = {
"run_name": "equil",
"charge_style": "none",
"rcut_min": 2.0 * u.angstrom,
"vdw_cutoff": 14.0 * u.angstrom,
"units": "sweeps",
"steps_per_sweep": 450,
"coord_freq": 50,
"prop_freq": 10,
"properties": thermo_props,
}
# Combine default/custom args and override default
custom_args = {**default_args, **custom_args}
mc.run(
system=system,
moveset=moveset,
run_type="equilibration",
run_length=250,
temperature=151.0 * u.K,
**custom_args,
)
mc.restart(
restart_from="equil",
run_name="prod",
run_type="production",
total_run_length=750,
)
def main():
# Load TON from a CIF file, replicate the cell
# Use mbuild to create a zeolite supercell from CIF
cif_path = resource_filename(
"mc_examples",
"realistic_workflows/zeolite_adsorption/resources/structures/TON.cif")
lattice = mbuild.lattice.load_cif(cif_path)
compound_dict = {
"Si": mbuild.Compound(name="Si"),
"O": mbuild.Compound(name="O"),
}
zeolite = lattice.populate(compound_dict, 2, 2, 6)
# Create a CG methane, load and apply ff
methane = mbuild.Compound(name="_CH4")
ff_path = resource_filename(
"mc_examples",
"realistic_workflows/zeolite_adsorption/resources/ffxml/adsorbates.xml",
)
ff_ads = foyer.Forcefield(ff_path)
methane_ff = ff_ads.apply(methane)
# Define pure fluid temperatures and chemical potentials
temperatures = [298 * u.K, 309 * u.K, 350 * u.K]
mus_fluid = np.arange(-49, -30, 3) * u.Unit("kJ/mol")
# Define the pressures at which we wish to study adsorption
pressures = [
0.01,
0.1,
0.25,
0.5,
0.75,
1.0,
2.0,
3.0,
5.0,
] * u.bar
# Select the zeolite ff
zeo_ff_names = ["june", "trappe"]
# Define a few custom_args that will be
# the same for all zeolite simulations
custom_args = {
"charge_style": "none",
"vdw_cutoff": 14.0 * u.angstrom,
"prop_freq": 10,
"max_molecules": [1, 10000],
}
# Loop over different zeolite ff's
for zeo_ff_name in zeo_ff_names:
# Load and apply ff to the zeolite structure
ff_path = resource_filename(
"mc_examples",
f"realistic_workflows/zeolite_adsorption/resources/ffxml/zeo_{zeo_ff_name}.xml",
)
ff_zeo = foyer.Forcefield(ff_path)
zeolite_ff = ff_zeo.apply(zeolite)
# Create the box_list, species_list, System, and MoveSet.
# These are not dependent upon (T,P) condition
box_list = [zeolite]
species_list = [zeolite_ff, methane_ff]
mols_in_boxes = [[1, 0]]
system = mc.System(box_list, species_list, mols_in_boxes=mols_in_boxes)
moveset = mc.MoveSet("gcmc", species_list)
# Loop over each temperature to compute an isotherm
for temperature in temperatures:
# Before we begin we must determine the
# chemical potentials required to achieve
# the desired pressures
fluid_pressures = []
for mu_fluid in mus_fluid:
dirname = f"fluid_T_{temperature:0.1f}_mu_{mu_fluid:.1f}".replace(
" ", "_").replace("/", "-")
thermo = ThermoProps(dirname + "/prod.out.prp")
fluid_pressures.append(np.mean(thermo.prop("Pressure")))
fluid_pressures = u.unyt_array(fluid_pressures)
# Fit a line to mu vs. P
slope, intercept, r_value, p_value, stderr = linregress(
np.log(fluid_pressures.to_value(u.bar)).flatten(),
y=mus_fluid.to_value("kJ/mol").flatten(),
)
# Determine chemical potentials
mus = (slope * np.log(pressures.in_units(u.bar)) +
intercept) * u.Unit("kJ/mol")
# Loop over each pressure and run the MC simulation!
for (pressure, mu) in zip(pressures, mus):
print(f"\nRun simulation: T = {temperature}, P = {pressure}\n")
dirname = f"zeo_ff_{zeo_ff_name}_T_{temperature:0.1f}_P_{pressure:0.2f}".replace(
" ", "_").replace("/", "-")
if not os.path.isdir(dirname):
os.mkdir(dirname)
else:
pass
with temporary_cd(dirname):
mc.run(
system=system,
moveset=moveset,
run_type="equil",
run_length=50000,
temperature=temperature,
run_name="equil",
chemical_potentials=["none", mu],
**custom_args,
)
mc.restart(
restart_from="equil",
run_name="prod",
run_type="prod",
total_run_length=200000,
)
def main():
# Create a water molecule with the spce geometry
water = spce_water
ff = foyer.Forcefield(get_ff("pore-spce-jc.xml"))
water_typed = ff.apply(water)
# Define conditions
temperature = 298.0 * u.K
# Define a range of (shifted) chemical potentials
mus_adsorbate = np.arange(-58, -42, 2) * u.Unit("kJ/mol")
# Define custom_args that are the same for all pure phase simulations
custom_args = {
"cutoff_style": "cut",
"charge_style": "ewald",
"rcut_min": 0.5 * u.angstrom,
"vdw_cutoff": 9.0 * u.angstrom,
"prop_freq": 10,
"angle_style": ["fixed"],
}
for mu_adsorbate in mus_adsorbate:
print(f"\nRun simulation: T = {temperature}, mu = {mu_adsorbate}\n")
dirname = f"T_{temperature:0.1f}_mu_{mu_adsorbate:.1f}".replace(
" ", "_"
).replace(
"/", "-"
)
if not os.path.isdir(dirname):
os.mkdir(dirname)
else:
pass
with temporary_cd(dirname):
# Box size depends on chemical potential
# Test simulations show mu' = -48 kJ/mol; p ~ 0.01 bar
# Employ IG law to estimate remaining box sizes; target 40 waters
mu_0 = -48 * u.kJ/u.mol
p_0 = 0.01 * u.bar
n_water_target = 40
p_ig = p_0 * np.exp((mu_adsorbate-mu_0)/(u.kb * temperature))
vol = n_water_target * u.kb * temperature / p_ig
boxl = (vol**(1./3.)).to_value("nm")
custom_args["charge_cutoff"] = 0.25 * boxl * u.nm
species_list = [water_typed]
box_list = [mbuild.Box([boxl, boxl, boxl])]
system = mc.System(
box_list, species_list,
)
moveset = mc.MoveSet("gcmc", species_list)
moveset.prob_regrow = 0.0
moveset.prob_translate = 0.3
moveset.prob_rotate = 0.3
moveset.prob_insert = 0.2
mc.run(
system=system,
moveset=moveset,
run_type="equil",
run_length=500000,
temperature=temperature,
run_name="equil",
chemical_potentials=[mu_adsorbate],
**custom_args,
)
mc.restart(
system=system,
moveset=moveset,
run_type="prod",
run_length=1000000,
temperature=temperature,
run_name="prod",
restart_name="equil",
chemical_potentials=[mu_adsorbate],
**custom_args,
)
box = mbuild.Box([box_length, box_length, box_length])
vapor_box = mbuild.fill_box(ethane, n_compounds=N_vapor, box=box)
# Initial liquid box from existing configuration
liquid_box = mbuild.load("liqbox_equil.gro")
N_liquid = len([child for child in liquid_box.children])
# Create the System and MoveSet
box_list = [liquid_box, vapor_box]
species_list = [ethane_ff]
mols_in_boxes = [[N_liquid], [N_vapor]]
system = mc.System(
box_list,
species_list,
mols_in_boxes=mols_in_boxes,
)
moveset = mc.MoveSet("gemc", species_list)
# Run the Monte Carlo simulation
mc.run(
system=system,
moveset=moveset,
run_type="equilibration",
run_length=500000,
temperature=temperature,
vdw_cutoff=10.0 * u.angstrom,
charge_cutoff=10.0 * u.angstrom,
mixing_rule="geometric",
)
def run_gcmc(
filled_pore,
pore_width,
temperature,
mu,
nsteps_nvt,
nsteps_gcmc,
pve_ion=mbuild.Compound(name="Na"),
nve_ion=mbuild.Compound(name="Cl"),
**custom_args,
):
"""Run desorption simulation at the specified temperature
and chemical potential
Parameters
----------
filled_pore : porebuilder.GraphenePoreSolvent
pore filled with water and (optional) ions
pore_width : u.unyt_quantity (length)
width of pore for restricted insertions
temperature: u.unyt_quantity (temperature)
desired temperature
mu : u.unyt_quantity (energy)
desired chemical potential for water
nsteps_nvt : int
number of MC steps for NVT equilibration
nsteps_gcmc : int
number of MC steps for GCMC simulation
pve_ion : mbuild.Compound, optional, default=Na
positive ion
nve_ion : mbuild.Compound, optional, default=Cl
negative ion
custom_args : opt, additional keyword arguments
provide additional custom keyword arguments to MoSDeF Cassandra
and override the default values
Returns
-------
None: runs simulation
"""
# Load foyer ff
ff = foyer.Forcefield(get_ff("pore-spce-jc.xml"))
# Extract just the pore and apply ff
empty_pore = filled_pore.children[0]
typed_pore = ff.apply(empty_pore)
# Create a water molecule with the spce geometry and apply ff
typed_water = ff.apply(spce_water)
typed_pve = ff.apply(pve_ion)
typed_nve = ff.apply(nve_ion)
# Determine the number of waters in the pore
n_water = len(
[child for child in filled_pore.children if child.name == "SOL"])
n_ion_pairs = int(
(len([child for child in filled_pore.children]) - 1 - n_water) / 2)
# Create box and species list
box_list = [filled_pore]
species_list = [typed_pore, typed_pve, typed_nve, typed_water]
# Specify mols at start of the simulation
mols_in_boxes = [[1, n_ion_pairs, n_ion_pairs, n_water]]
# Create MC system
system = mc.System(box_list, species_list, mols_in_boxes=mols_in_boxes)
moves = mc.MoveSet("nvt", species_list)
# Set move probabilities
moves.prob_translate = 0.5
moves.prob_rotate = 0.5
moves.prob_regrow = 0.0
# Set thermodynamic properties
thermo_props = [
"energy_total",
"energy_intervdw",
"energy_interq",
"nmols",
]
default_args = {
"run_name": "nvt",
"cutoff_style": "cut",
"charge_style": "ewald",
"rcut_min": 0.5 * u.angstrom,
"vdw_cutoff": 9.0 * u.angstrom,
"charge_cutoff": 9.0 * u.angstrom,
"properties": thermo_props,
"angle_style": ["harmonic", "harmonic", "harmonic", "fixed"],
"coord_freq": 100000,
"prop_freq": 1000,
}
custom_args = {**default_args, **custom_args}
# Run NVT equilibration
mc.run(
system=system,
moveset=moves,
run_type="equilibration",
run_length=nsteps_nvt,
temperature=temperature,
**custom_args,
)
# Create MC system
equilibrated_box = load_final_xyz_frame("nvt.out.xyz")
box_list = [equilibrated_box]
system = mc.System(box_list, species_list, mols_in_boxes=mols_in_boxes)
moves = mc.MoveSet("gcmc", species_list)
# Set move probabilities
moves.prob_translate = 0.25
moves.prob_rotate = 0.25
moves.prob_insert = 0.25
moves.prob_regrow = 0.0
# Make Na/Cl NOT insertable
moves.insertable[1] = False
moves.insertable[2] = False
# Specify the restricted insertion
restricted_type = [[None, None, None, "slitpore"]]
restricted_value = [[None, None, None, 0.5 * pore_width]]
moves.add_restricted_insertions(species_list, restricted_type,
restricted_value)
# Run GCMC
custom_args["run_name"] = "gcmc"
mc.run(
system=system,
moveset=moves,
run_type="equilibration",
run_length=nsteps_gcmc,
temperature=temperature,
chemical_potentials=["none", "none", "none", mu],
**custom_args,
)
def main():
# Create a CG methane, load and apply ff
methane = mbuild.Compound(name="_CH4")
ff_path = resource_filename(
"mc_examples",
"realistic_workflows/zeolite_adsorption/resources/ffxml/adsorbates.xml",
)
ff_ads = foyer.Forcefield(ff_path)
methane_ff = ff_ads.apply(methane)
# Define a few keyword args that will be the
# same for all fluid phase simulations
custom_args = {
"charge_style": "none",
"vdw_cutoff": 14.0 * u.angstrom,
"prop_freq": 10,
}
# Define temperatures and chemical potential values
# for the single phase GCMC simulations
temperatures = [298 * u.K, 309 * u.K, 350 * u.K]
mus = np.arange(-49, -30, 3) * u.Unit("kJ/mol")
# Loop over temperatures and mus and run simulations
for temperature in temperatures:
for mu in mus:
# For each simulation -- first estimate
# the box volume to target ~40 molecules
n_methane_target = 40
beta = 1.0 / (u.kb * temperature)
mass = 16.04 * u.amu
debroglie = np.sqrt(2 * np.pi * u.hbar**2 * beta / mass)
vol = n_methane_target * debroglie**3 * np.exp(
-beta.to("mol/kJ") * mu)
boxl = (vol**(1.0 / 3.0)).to_value("nm")
if boxl < 2.0 * custom_args["vdw_cutoff"].to_value("nm"):
boxl = 2.0 * custom_args["vdw_cutoff"].to_value("nm")
# Define the species list, box list, system, moveset
# We start with an empty box
species_list = [methane_ff]
box_list = [mbuild.Box([boxl, boxl, boxl])]
system = mc.System(box_list, species_list)
moveset = mc.MoveSet("gcmc", species_list)
# Create a new directory, temporary cd, and run
# the equilibration and production simulations!
print(f"\nRun simulation: T = {temperature}, mu = {mu}\n")
dirname = f"fluid_T_{temperature:0.1f}_mu_{mu:.1f}".replace(
" ", "_").replace("/", "-")
if not os.path.isdir(dirname):
os.mkdir(dirname)
else:
pass
with temporary_cd(dirname):
mc.run(
system=system,
moveset=moveset,
run_type="equil",
run_length=50000,
temperature=temperature,
run_name="equil",
chemical_potentials=[mu],
**custom_args,
)
mc.restart(
restart_from="equil",
run_name="prod",
run_type="prod",
total_run_length=400000,
)
