Coverage-dependent thermochemistry for catalysis

rmgpy/chemkin.pyx

@@ -1865,7 +1865,7 @@ def write_kinetics_entry(reaction, species_list, verbose=True, java_library=Fals
         for species, cov_params in kinetics.coverage_dependence.items():
             label = get_species_identifier(species)
             string += f'    COV / {label:<41} '
-            string += f"{cov_params['a']:<9.3g} {cov_params['m']:<9.3g} {cov_params['E'].value_si/4184.:<9.3f} /\n"
+            string += f"{cov_params['a'].value_si:<9.3g} {cov_params['m'].value_si:<9.3g} {cov_params['E'].value_si/4184.:<9.3f} /\n"
 
     if isinstance(kinetics, (_kinetics.ThirdBody, _kinetics.Lindemann, _kinetics.Troe)):
         # Write collider efficiencies

rmgpy/rmg/input.py

@@ -108,7 +108,8 @@ def database(
 def catalyst_properties(bindingEnergies=None,
                         surfaceSiteDensity=None,
                         metal=None,
-                        coverageDependence=False):
+                        coverageDependence=False,
+                        thermoCoverageDependence=False,):
     """
     Specify the properties of the catalyst.
     Binding energies of C,H,O,N atoms, and the surface site density.
@@ -155,6 +156,7 @@ def catalyst_properties(bindingEnergies=None,
     else:
         logging.info("Coverage dependence is turned OFF")
     rmg.coverage_dependence = coverageDependence
+    rmg.thermo_coverage_dependence = thermoCoverageDependence
 
 def convert_binding_energies(binding_energies):
     """
@@ -1076,7 +1078,8 @@ def surface_reactor(temperature,
                             sensitive_species=sensitive_species,
                             sensitivity_threshold=sensitivityThreshold,
                             sens_conditions=sens_conditions,
-                            coverage_dependence=rmg.coverage_dependence)
+                            coverage_dependence=rmg.coverage_dependence,
+                            thermo_coverage_dependence=rmg.thermo_coverage_dependence)
     rmg.reaction_systems.append(system)
     system.log_initial_conditions(number=len(rmg.reaction_systems))
 

rmgpy/rmg/main.py

@@ -50,6 +50,7 @@
 import yaml
 from cantera import ck2yaml
 from scipy.optimize import brute
+import cantera as ct
 
 import rmgpy.util as util
 from rmgpy.rmg.model import Species, CoreEdgeReactionModel
@@ -192,6 +193,7 @@ def clear(self):
         self.surface_site_density = None
         self.binding_energies = None
         self.coverage_dependence = False
+        self.thermo_coverage_dependence = False
         self.forbidden_structures = []
 
         self.reaction_model = None
@@ -276,6 +278,7 @@ def load_input(self, path=None):
             self.reaction_model.core.phase_system.phases["Surface"].site_density = self.surface_site_density.value_si
             self.reaction_model.edge.phase_system.phases["Surface"].site_density = self.surface_site_density.value_si
         self.reaction_model.coverage_dependence = self.coverage_dependence
+        self.reaction_model.thermo_coverage_dependence = self.thermo_coverage_dependence
 
         self.reaction_model.verbose_comments = self.verbose_comments
         self.reaction_model.save_edge_species = self.save_edge_species
@@ -1212,6 +1215,44 @@ def execute(self, initialize=True, **kwargs):
                     os.path.join(self.output_directory, "chemkin", "chem_annotated-gas.inp"),
                     surface_file=(os.path.join(self.output_directory, "chemkin", "chem_annotated-surface.inp")),
                 )
+                if self.thermo_coverage_dependence:
+                    # add thermo coverage dependence to Cantera files
+                    chem_yaml_path = os.path.join(self.output_directory, "cantera", "chem.yaml")
+                    gas = ct.Solution(chem_yaml_path, "gas")
+                    surf = ct.Interface(chem_yaml_path, "surface1", [gas])
+                    with open(chem_yaml_path, 'r') as f:
+                        content = yaml.load(f, Loader=yaml.FullLoader)
+
+                    content['phases'][1]['reference-state-coverage'] = 0.11
+                    content['phases'][1]['thermo'] = 'coverage-dependent-surface'
+
+                    for s in self.reaction_model.core.species:
+                        if s.contains_surface_site() and s.thermo.thermo_coverage_dependence:
+                            for dep_sp, parameters in s.thermo.thermo_coverage_dependence.items():
+                                mol = Molecule().from_adjacency_list(dep_sp)
+                                for sp in self.reaction_model.core.species:
+                                    if sp.is_isomorphic(mol, strict=False):
+                                        parameters['units'] = {'energy':'J', 'quantity':'mol'}
+                                        parameters['enthalpy-coefficients'] = [value.value_si for value in parameters['enthalpy-coefficients']]
+                                        parameters['entropy-coefficients'] = [value.value_si for value in parameters['entropy-coefficients']]
+                                        try:
+                                            content["species"][gas.n_species+surf.species_index(sp.to_chemkin())]['coverage-dependencies'][sp.to_chemkin()] = parameters
+                                        except KeyError:
+                                            content["species"][gas.n_species+surf.species_index(sp.to_chemkin())]['coverage-dependencies'] = {sp.to_chemkin(): parameters}
+
+                    annotated_yaml_path = os.path.join(self.output_directory, "cantera", "chem_annotated.yaml")
+                    with open(annotated_yaml_path, 'r') as f:
+                        annotated_content = yaml.load(f, Loader=yaml.FullLoader)
+
+                    annotated_content['phases'] = content['phases']
+                    annotated_content['species'] = content['species']
+
+                    with open(chem_yaml_path, 'w') as output_f:
+                        yaml.dump(content, output_f, sort_keys=False)
+
+                    with open(annotated_yaml_path, 'w') as output_f:
+                        yaml.dump(annotated_content, output_f, sort_keys=False)
+
             else:  # gas phase only
                 self.generate_cantera_files(os.path.join(self.output_directory, "chemkin", "chem.inp"))
                 self.generate_cantera_files(os.path.join(self.output_directory, "chemkin", "chem_annotated.inp"))

rmgpy/solver/surface.pyx

@@ -43,6 +43,8 @@ cimport rmgpy.constants as constants
 from rmgpy.quantity import Quantity
 from rmgpy.quantity cimport ScalarQuantity
 from rmgpy.solver.base cimport ReactionSystem
+import copy
+from rmgpy.molecule import Molecule
 
 cdef class SurfaceReactor(ReactionSystem):
     """
@@ -66,9 +68,13 @@ cdef class SurfaceReactor(ReactionSystem):
     cdef public ScalarQuantity surface_site_density
     cdef public np.ndarray reactions_on_surface  # (catalyst surface, not core/edge surface)
     cdef public np.ndarray species_on_surface  # (catalyst surface, not core/edge surface)
+    cdef public np.ndarray thermo_coeff_matrix
+    cdef public np.ndarray stoi_matrix
 
     cdef public bint coverage_dependence
     cdef public dict coverage_dependencies
+    cdef public bint thermo_coverage_dependence
+
 
 
     def __init__(self,
@@ -84,6 +90,7 @@ cdef class SurfaceReactor(ReactionSystem):
                  sensitivity_threshold=1e-3,
                  sens_conditions=None,
                  coverage_dependence=False,
+                 thermo_coverage_dependence=False,
                  ):
         ReactionSystem.__init__(self,
                                 termination,
@@ -103,6 +110,7 @@ cdef class SurfaceReactor(ReactionSystem):
         self.surface_volume_ratio = Quantity(surface_volume_ratio)
         self.surface_site_density = Quantity(surface_site_density)
         self.coverage_dependence = coverage_dependence
+        self.thermo_coverage_dependence = thermo_coverage_dependence
         self.V = 0  # will be set from ideal gas law in initialize_model
         self.constant_volume = True
         self.sens_conditions = sens_conditions
@@ -166,6 +174,10 @@ cdef class SurfaceReactor(ReactionSystem):
                                        )
         cdef np.ndarray[np.int_t, ndim=1] species_on_surface, reactions_on_surface
         cdef Py_ssize_t index
+        cdef np.ndarray thermo_coeff_matrix = np.zeros((len(self.species_index), len(self.species_index), 6), dtype=np.float64)
+        cdef np.ndarray stoi_matrix = np.zeros((self.reactant_indices.shape[0], len(self.species_index)), dtype=np.float64)
+        if self.thermo_coverage_dependence:
+            self.thermo_coeff_matrix = thermo_coeff_matrix
         #: 1 if it's on a surface, 0 if it's in the gas phase
         reactions_on_surface = np.zeros((self.num_core_reactions + self.num_edge_reactions), int)
         species_on_surface = np.zeros((self.num_core_species), int)
@@ -195,6 +207,49 @@ cdef class SurfaceReactor(ReactionSystem):
                 means that Species with index 2 in the current simulation is used in
                 Reaction 3 with parameters a=0.1, m=-1, E=12 kJ/mol
                 """
+        for sp, sp_index in self.species_index.items():
+            if sp.contains_surface_site():
+                if self.thermo_coverage_dependence and sp.thermo.thermo_coverage_dependence:
+                    for spec, parameters in sp.thermo.thermo_coverage_dependence.items():
+                        molecule = Molecule().from_adjacency_list(spec)
+                        for species in self.species_index.keys():
+                            if species.is_isomorphic(molecule, strict=False):
+                                species_index = self.species_index[species]
+                                enthalpy_coeff = np.array([p.value_si for p in parameters['enthalpy-coefficients']])
+                                entropy_coeff = np.array([p.value_si for p in parameters['entropy-coefficients']])
+                                thermo_polynomials = np.concatenate((enthalpy_coeff, entropy_coeff), axis=0)
+                                self.thermo_coeff_matrix[sp_index, species_index] = [x for x in thermo_polynomials]
+        # create a stoichiometry matrix for reaction enthalpy and entropy correction 
+        # due to thermodynamic coverage dependence
+        if self.thermo_coverage_dependence:
+            ir = self.reactant_indices
+            ip = self.product_indices
+            for rxn_id, rxn_stoi_num in enumerate(stoi_matrix):
+                if ir[rxn_id, 0] >= self.num_core_species or ir[rxn_id, 1] >= self.num_core_species or ir[rxn_id, 2] >= self.num_core_species:
+                    continue
+                elif ip[rxn_id, 0] >= self.num_core_species or ip[rxn_id, 1] >= self.num_core_species or ip[rxn_id, 2] >= self.num_core_species:
+                    continue
+                else:
+                    if ir[rxn_id, 1] == -1:  # only one reactant
+                        rxn_stoi_num[ir[rxn_id, 0]] += -1
+                    elif ir[rxn_id, 2] == -1:  # only two reactants
+                        rxn_stoi_num[ir[rxn_id, 0]] += -1
+                        rxn_stoi_num[ir[rxn_id, 1]] += -1
+                    else:  # three reactants
+                        rxn_stoi_num[ir[rxn_id, 0]] += -1
+                        rxn_stoi_num[ir[rxn_id, 1]] += -1
+                        rxn_stoi_num[ir[rxn_id, 2]] += -1
+                    if ip[rxn_id, 1] == -1:  # only one product
+                        rxn_stoi_num[ip[rxn_id, 0]] += 1
+                    elif ip[rxn_id, 2] == -1:  # only two products
+                        rxn_stoi_num[ip[rxn_id, 0]] += 1
+                        rxn_stoi_num[ip[rxn_id, 1]] += 1
+                    else:  # three products
+                        rxn_stoi_num[ip[rxn_id, 0]] += 1
+                        rxn_stoi_num[ip[rxn_id, 1]] += 1
+                        rxn_stoi_num[ip[rxn_id, 2]] += 1
+            self.stoi_matrix = stoi_matrix
+
         self.species_on_surface = species_on_surface
         self.reactions_on_surface = reactions_on_surface
 
@@ -378,9 +433,6 @@ cdef class SurfaceReactor(ReactionSystem):
         cdef np.ndarray[np.float64_t, ndim=2] jacobian, dgdk
         cdef list list_of_coverage_deps
         cdef double surface_site_fraction, total_sites, a, m, E
-
-
-
         ir = self.reactant_indices
         ip = self.product_indices
         equilibrium_constants = self.Keq
@@ -414,14 +466,33 @@ cdef class SurfaceReactor(ReactionSystem):
         V = self.V  # constant volume reactor
         A = self.V * surface_volume_ratio_si  # area
         total_sites = self.surface_site_density.value_si * A  # todo: double check units
-
         for j in range(num_core_species):
             if species_on_surface[j]:
                 C[j] = (N[j] / V) / surface_volume_ratio_si
             else:
                 C[j] = N[j] / V
             #: surface species are in mol/m2, gas phase are in mol/m3
             core_species_concentrations[j] = C[j]
+
+        # Thermodynamic coverage dependence
+        if self.thermo_coverage_dependence:
+            coverages = []
+            for i in range(len(N)):
+                if species_on_surface[i]:
+                    surface_site_fraction = N[i] / total_sites
+                else:
+                    surface_site_fraction = 0
+                coverages.append(surface_site_fraction)
+            coverages = np.array(coverages)
+            thermo_dep_coverage = np.stack([coverages, coverages**2, coverages**3, -self.T.value_si*coverages, -self.T.value_si*coverages**2, -self.T.value_si*coverages**3])
+            free_energy_coverage_corrections = []
+            for matrix in self.thermo_coeff_matrix:
+                sp_free_energy_correction = np.diag(np.dot(matrix, thermo_dep_coverage)).sum()
+                free_energy_coverage_corrections.append(sp_free_energy_correction)
+            rxns_free_energy_change = np.diag(np.dot(self.stoi_matrix, np.transpose(np.array([free_energy_coverage_corrections]))))
+            corrected_K_eq = copy.deepcopy(self.Keq)
+            corrected_K_eq *= np.exp(-1 * rxns_free_energy_change / (constants.R * self.T.value_si))
+            kr = kf / corrected_K_eq
 
         # Coverage dependence
         coverage_corrections = np.ones_like(kf, float)

rmgpy/thermo/nasa.pxd

@@ -56,6 +56,7 @@ cdef class NASAPolynomial(HeatCapacityModel):
 cdef class NASA(HeatCapacityModel):
 
     cdef public NASAPolynomial poly1, poly2, poly3
+    cdef public dict _thermo_coverage_dependence
 
     cpdef NASAPolynomial select_polynomial(self, double T)