Fix getCoverages for multi-site species

Cantera · Aug 9, 2022 · 6e0028e · 6e0028e
1 parent eedcbf9
commit 6e0028e
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Showing 3 changed files with 62 additions and 2 deletions.
diff --git a/src/thermo/SurfPhase.cpp b/src/thermo/SurfPhase.cpp
@@ -250,9 +250,15 @@ void SurfPhase::setCoveragesNoNorm(const doublereal* theta)
 
 void SurfPhase::getCoverages(doublereal* theta) const
 {
-    getConcentrations(theta);
+    double sum_X = 0.0;
+    double sum_X_s = 0.0;
+    getMoleFractions(theta);
     for (size_t k = 0; k < m_kk; k++) {
-        theta[k] *= size(k)/m_n0;
+        sum_X += theta[k];
+        sum_X_s += theta[k] * size(k);
+    }
+    for (size_t k = 0; k < m_kk; k++) {
+        theta[k] *= size(k) * sum_X / sum_X_s;
     }
 }
 

diff --git a/test/data/surface-phases.yaml b/test/data/surface-phases.yaml
@@ -13,6 +13,18 @@ phases:
   site-density: 2.7063e-9 mol/cm^2
   state: {T: 900 K, P: 1 atm, coverages: {Pt(s): 0.5, H(s): 0.4, O(s): 0.1}}
 
+- name: Pt-multi-sites
+  thermo: ideal-surface
+  adjacent-phases: [gas]
+  kinetics: surface
+  reactions: [Pt-reactions, Pt-multisite-reactions]
+  species: [{Pt-surf-species: all}, {multi-site-species: all}]
+  site-density: 2.7063e-9 mol/cm^2
+  state:
+    T: 900 K
+    P: 1 atm
+    coverages: {Pt(s): 0.35, H(s): 0.4, O(s): 0.1, O2(s): 0.15}
+
 - name: TPB
   thermo: edge
   species: [{tpb-species: [(tpb)]}]
@@ -102,6 +114,19 @@ Pt-surf-species:
     - [1.9454180E+00, 9.1761647E-04, -1.1226719E-07, -9.9099624E-11,
        2.4307699E-14, -1.4005187E+04, -1.1531663E+01]
 
+multi-site-species:
+- name: O2(s)
+  composition: {O: 2, Pt: 2}
+  sites: 2
+  thermo:
+    model: NASA7
+    temperature-ranges: [300, 1000, 3000]
+    data:
+    - [-9.4986904E-01, 7.4042305E-03, -1.0451424E-06, -6.1120420E-09,
+       3.3787992E-12, -1.3209912E+04, 3.6137905E+00]
+    - [1.9454180E+00, 9.1761647E-04, -1.1226719E-07, -9.9099624E-11,
+       2.4307699E-14, -1.4005187E+04, -1.1531663E+01]
+
 
 tpb-species:
 - name: (tpb)
@@ -120,6 +145,9 @@ Pt-reactions:
 - equation: H + Pt(s) => H(s)
   sticking-coefficient: [1.0, 0.0, 0.0]
 
+Pt-multisite-reactions:
+- equation: 2 O(s) <=> O2(s)
+  rate-constant: {A: 3.1e9 cm^2/mol/s, b: 0.0, Ea: 0.0}
 
 graphite-anode-species:
 - name: EC(e)

diff --git a/test/python/test_thermo.py b/test/python/test_thermo.py
@@ -1130,6 +1130,32 @@ def test_coverages_dict(self):
         self.assertNear(C[self.interface.species_index('c6*M')], 0.75)
 
 
+class TestInterfacePhase2(utilities.CanteraTest):
+    """ Test special cases of interface phases """
+    def test_multi_site_species(self):
+        surf = ct.Interface("surface-phases.yaml", "Pt-multi-sites")
+        # O2(s) consumes two surface sites
+        surf.coverages = {"Pt(s)": 0.5, "H(s)": 0.1, "O2(s)": 0.4}
+        X = surf.mole_fraction_dict()
+        moles = 0.5 + 0.1 + 0.4 / 2
+        assert np.isclose(X["Pt(s)"], 0.5 / moles)
+        assert np.isclose(X["H(s)"], 0.1 / moles)
+        assert np.isclose(X["O2(s)"], 0.2 / moles)
+
+    def test_multi_site_unnormalized(self):
+        surf = ct.Interface("surface-phases.yaml", "Pt-multi-sites")
+        theta = [0.5, 0.1, 0.1, 0.32]
+        surf.set_unnormalized_coverages(theta)
+        self.assertArrayNear(surf.coverages, theta)
+
+        X_unnormalized = surf.X
+        assert np.isclose(sum(theta), sum(surf.X))
+
+        surf.coverages = theta
+        X_normalized = surf.X
+        self.assertArrayNear(X_normalized * sum(theta), X_unnormalized)
+
+
 class TestPlasmaPhase(utilities.CanteraTest):
     def setUp(self):
         self.phase = ct.Solution('oxygen-plasma.yaml',