[Input] Create FixedChemPot objects from YAML definitions

include/cantera/thermo/FixedChemPotSSTP.h

@@ -318,6 +318,8 @@ public:
 
     virtual void initThermoXML(XML_Node& phaseNode, const std::string& id);
 
+    virtual void initThermo();
+
     //! Set the equation of state parameters
     /*!
      * @internal

src/thermo/FixedChemPotSSTP.cpp

@@ -212,6 +212,14 @@ void FixedChemPotSSTP::initThermoXML(XML_Node& phaseNode, const std::string& id_
     }
 }
 
+void FixedChemPotSSTP::initThermo()
+{
+    if (m_input.hasKey("chemical-potential")) {
+        chemPot_ = m_input.convert("chemical-potential", "J/kmol");
+    }
+    SingleSpeciesTP::initThermo();
+}
+
 void FixedChemPotSSTP::setParameters(int n, doublereal* const c)
 {
     chemPot_ = c[0];

src/thermo/ThermoFactory.cpp

@@ -69,6 +69,7 @@ ThermoFactory::ThermoFactory()
     reg("Margules", []() { return new MargulesVPSSTP(); });
     reg("IonsFromNeutralMolecule", []() { return new IonsFromNeutralVPSSTP(); });
     reg("FixedChemPot", []() { return new FixedChemPotSSTP(); });
+    m_synonyms["fixed-chemical-potential"] = "FixedChemPot";
     reg("Redlich-Kister", []() { return new RedlichKisterVPSSTP(); });
     reg("RedlichKwong", []() { return new RedlichKwongMFTP(); });
     m_synonyms["RedlichKwongMFTP"] = "RedlichKwong";

test/data/thermo-models.yaml

@@ -14,6 +14,11 @@ phases:
   thermo: water-IAPWS95
   species: [H2O(l)]
 
+- name: Li-fixed
+  thermo: fixed-chemical-potential
+  species: [Li]
+  chemical-potential: -2.3e7 J/kmol
+
 species:
 - name: NaCl(s)
   composition: {Na: 1, Cl: 1}
@@ -42,3 +47,6 @@ species:
 
 - name: H2O(l)
   composition: {H: 2, O: 1}
+
+- name: Li
+  composition: {Li: 1}

test/thermo/thermoFromYaml.cpp

@@ -102,3 +102,14 @@ TEST(ThermoFromYaml, WaterSSTP)
     EXPECT_NEAR(thermo->density(), 973.7736331, 1e-6);
     EXPECT_NEAR(thermo->enthalpy_mass(), -15649442.2898854, 1e-6);
 }
+
+TEST(ThermoFromYaml, FixedChemPot)
+{
+    AnyMap infile = AnyMap::fromYamlFile("thermo-models.yaml");
+    auto phaseNodes = infile["phases"].asMap("name");
+    auto thermo = newPhase(*phaseNodes.at("Li-fixed"), infile);
+    EXPECT_EQ(thermo->nSpecies(), (size_t) 1);
+    double mu;
+    thermo->getChemPotentials(&mu);
+    EXPECT_DOUBLE_EQ(mu, -2.3e7);
+}