diff --git a/applications/solvers/combustion/PDRFoam/createFields.H b/applications/solvers/combustion/PDRFoam/createFields.H
index d1d8c80627..fc90852f22 100644
--- a/applications/solvers/combustion/PDRFoam/createFields.H
+++ b/applications/solvers/combustion/PDRFoam/createFields.H
@@ -7,7 +7,7 @@ autoPtr<psiuReactionThermo> pThermo
 psiuReactionThermo& thermo = pThermo();
 thermo.validate(args.executable(), "ha", "ea");
 
-basicSpecieMixture& composition = thermo.composition();
+basicCombustionMixture& composition = thermo.composition();
 
 volScalarField rho
 (
diff --git a/applications/solvers/combustion/XiFoam/createFields.H b/applications/solvers/combustion/XiFoam/createFields.H
index 9e60740b7e..3bfc22fec3 100644
--- a/applications/solvers/combustion/XiFoam/createFields.H
+++ b/applications/solvers/combustion/XiFoam/createFields.H
@@ -7,7 +7,7 @@ autoPtr<psiuReactionThermo> pThermo
 psiuReactionThermo& thermo = pThermo();
 thermo.validate(args.executable(), "ha", "ea");
 
-basicSpecieMixture& composition = thermo.composition();
+basicCombustionMixture& composition = thermo.composition();
 
 volScalarField rho
 (
diff --git a/applications/solvers/heatTransfer/chtMultiRegionFoam/fluid/setRegionFluidFields.H b/applications/solvers/heatTransfer/chtMultiRegionFoam/fluid/setRegionFluidFields.H
index d12f3398f1..b6baaaa9a4 100644
--- a/applications/solvers/heatTransfer/chtMultiRegionFoam/fluid/setRegionFluidFields.H
+++ b/applications/solvers/heatTransfer/chtMultiRegionFoam/fluid/setRegionFluidFields.H
@@ -5,7 +5,7 @@
     rhoReactionThermo& thermo = thermoFluid[i];
     thermo.validate(args.executable(), "h", "e");
 
-    basicMultiComponentMixture& composition = thermo.composition();
+    basicSpecieMixture& composition = thermo.composition();
     PtrList<volScalarField>& Y = composition.Y();
 
     label inertIndex = -1;
diff --git a/src/combustionModels/radiationModels/sootModels/mixtureFraction/mixtureFraction.C b/src/combustionModels/radiationModels/sootModels/mixtureFraction/mixtureFraction.C
index e24b123897..903618f735 100644
--- a/src/combustionModels/radiationModels/sootModels/mixtureFraction/mixtureFraction.C
+++ b/src/combustionModels/radiationModels/sootModels/mixtureFraction/mixtureFraction.C
@@ -98,7 +98,7 @@ Foam::radiationModels::sootModels::mixtureFraction<ThermoType>::mixtureFraction
         const label speciei = reaction.rhs()[i].index;
         const scalar stoichCoeff = reaction.rhs()[i].stoichCoeff;
         Xi[i] = mag(stoichCoeff)/totalMol;
-        Wm += Xi[i]*mixture.speciesData()[speciei].W();
+        Wm += Xi[i]*mixture.specieThermos()[speciei].W();
     }
 
     scalarList Yprod0(mixture.species().size(), 0.0);
@@ -106,7 +106,7 @@ Foam::radiationModels::sootModels::mixtureFraction<ThermoType>::mixtureFraction
     forAll(reaction.rhs(), i)
     {
         const label speciei = reaction.rhs()[i].index;
-        Yprod0[speciei] = mixture.speciesData()[speciei].W()/Wm*Xi[i];
+        Yprod0[speciei] = mixture.specieThermos()[speciei].W()/Wm*Xi[i];
     }
 
     const scalar XSoot = nuSoot_/totalMol;
diff --git a/src/combustionModels/singleStepCombustion/singleStepCombustion.C b/src/combustionModels/singleStepCombustion/singleStepCombustion.C
index e742b12743..7eb0121ee7 100644
--- a/src/combustionModels/singleStepCombustion/singleStepCombustion.C
+++ b/src/combustionModels/singleStepCombustion/singleStepCombustion.C
@@ -39,14 +39,14 @@ template<class ReactionThermo, class ThermoType>
 void singleStepCombustion<ReactionThermo, ThermoType>::calculateqFuel()
 {
     const Reaction<ThermoType>& reaction = reaction_();
-    const scalar Wu = mixture_.speciesData()[fuelIndex_].W();
+    const scalar Wu = mixture_.specieThermos()[fuelIndex_].W();
 
     forAll(reaction.lhs(), i)
     {
         const label speciei = reaction.lhs()[i].index;
         const scalar stoichCoeff = reaction.lhs()[i].stoichCoeff;
         specieStoichCoeffs_[speciei] = -stoichCoeff;
-        qFuel_.value() += mixture_.speciesData()[speciei].hc()*stoichCoeff/Wu;
+        qFuel_.value() += mixture_.specieThermos()[speciei].hc()*stoichCoeff/Wu;
     }
 
     forAll(reaction.rhs(), i)
@@ -54,7 +54,7 @@ void singleStepCombustion<ReactionThermo, ThermoType>::calculateqFuel()
         const label speciei = reaction.rhs()[i].index;
         const scalar stoichCoeff = reaction.rhs()[i].stoichCoeff;
         specieStoichCoeffs_[speciei] = stoichCoeff;
-        qFuel_.value() -= mixture_.speciesData()[speciei].hc()*stoichCoeff/Wu;
+        qFuel_.value() -= mixture_.specieThermos()[speciei].hc()*stoichCoeff/Wu;
         specieProd_[speciei] = -1;
     }
 
@@ -66,17 +66,17 @@ template<class ReactionThermo, class ThermoType>
 void singleStepCombustion<ReactionThermo, ThermoType>:: massAndAirStoichRatios()
 {
     const label O2Index = mixture_.species()["O2"];
-    const scalar Wu = mixture_.speciesData()[fuelIndex_].W();
+    const scalar Wu = mixture_.specieThermos()[fuelIndex_].W();
 
     stoicRatio_ =
-       (mixture_.speciesData()[inertIndex_].W()
+       (mixture_.specieThermos()[inertIndex_].W()
       * specieStoichCoeffs_[inertIndex_]
-      + mixture_.speciesData()[O2Index].W()
+      + mixture_.specieThermos()[O2Index].W()
       * mag(specieStoichCoeffs_[O2Index]))
       / (Wu*mag(specieStoichCoeffs_[fuelIndex_]));
 
     s_ =
-        (mixture_.speciesData()[O2Index].W()
+        (mixture_.specieThermos()[O2Index].W()
       * mag(specieStoichCoeffs_[O2Index]))
       / (Wu*mag(specieStoichCoeffs_[fuelIndex_]));
 
@@ -105,13 +105,13 @@ void singleStepCombustion<ReactionThermo, ThermoType>:: calculateMaxProducts()
     {
         const label speciei = reaction.rhs()[i].index;
         Xi[i] = mag(specieStoichCoeffs_[speciei])/totalMol;
-        Wm += Xi[i]*mixture_.speciesData()[speciei].W();
+        Wm += Xi[i]*mixture_.specieThermos()[speciei].W();
     }
 
     forAll(reaction.rhs(), i)
     {
         const label speciei = reaction.rhs()[i].index;
-        Yprod0_[speciei] =  mixture_.speciesData()[speciei].W()/Wm*Xi[i];
+        Yprod0_[speciei] =  mixture_.specieThermos()[speciei].W()/Wm*Xi[i];
     }
 
     Info << "Maximum products mass concentrations:" << nl;
@@ -128,8 +128,8 @@ void singleStepCombustion<ReactionThermo, ThermoType>:: calculateMaxProducts()
     {
         specieStoichCoeffs_[i] =
             specieStoichCoeffs_[i]
-          * mixture_.speciesData()[i].W()
-          / (mixture_.speciesData()[fuelIndex_].W()
+          * mixture_.specieThermos()[i].W()
+          / (mixture_.specieThermos()[fuelIndex_].W()
           * mag(specieStoichCoeffs_[fuelIndex_]));
     }
 }
@@ -156,7 +156,7 @@ singleStepCombustion<ReactionThermo, ThermoType>::singleStepCombustion
         Reaction<ThermoType>::New
         (
             mixture_.species(),
-            mixture_.speciesData(),
+            mixture_.specieThermos(),
             this->subDict("reaction")
         )
     ),
diff --git a/src/thermophysicalModels/basic/mixtures/basicMixture/basicMixture.H b/src/thermophysicalModels/basic/mixtures/basicMixture/basicMixture.H
index 512c6ac6ef..cc72a8935a 100644
--- a/src/thermophysicalModels/basic/mixtures/basicMixture/basicMixture.H
+++ b/src/thermophysicalModels/basic/mixtures/basicMixture/basicMixture.H
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2018 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2020 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -42,6 +42,7 @@ namespace Foam
 
 class fvMesh;
 class dictionary;
+class word;
 
 /*---------------------------------------------------------------------------*\
                         Class basicMixture Declaration
diff --git a/src/thermophysicalModels/chemistryModel/chemistryModel/StandardChemistryModel/StandardChemistryModel.C b/src/thermophysicalModels/chemistryModel/chemistryModel/StandardChemistryModel/StandardChemistryModel.C
index a7942dc17e..de221c6c5b 100644
--- a/src/thermophysicalModels/chemistryModel/chemistryModel/StandardChemistryModel/StandardChemistryModel.C
+++ b/src/thermophysicalModels/chemistryModel/chemistryModel/StandardChemistryModel/StandardChemistryModel.C
@@ -39,10 +39,10 @@ Foam::StandardChemistryModel<ReactionThermo, ThermoType>::StandardChemistryModel
     BasicChemistryModel<ReactionThermo>(thermo),
     ODESystem(),
     Y_(this->thermo().composition().Y()),
-    specieThermo_
+    specieThermos_
     (
         dynamic_cast<const multiComponentMixture<ThermoType>&>
-            (this->thermo()).speciesData()
+            (this->thermo()).specieThermos()
     ),
     reactions_
     (
@@ -50,7 +50,7 @@ Foam::StandardChemistryModel<ReactionThermo, ThermoType>::StandardChemistryModel
         (
             this->thermo()
         ).species(),
-        specieThermo_,
+        specieThermos_,
         this->mesh(),
         *this
     ),
@@ -175,21 +175,21 @@ void Foam::StandardChemistryModel<ReactionThermo, ThermoType>::derivatives
     scalar cSum = 0;
     for (label i = 0; i < nSpecie_; i++)
     {
-        const scalar W = specieThermo_[i].W();
+        const scalar W = specieThermos_[i].W();
         cSum += c_[i];
         rho += W*c_[i];
     }
     scalar cp = 0;
     for (label i=0; i<nSpecie_; i++)
     {
-        cp += c_[i]*specieThermo_[i].cp(p, T);
+        cp += c_[i]*specieThermos_[i].cp(p, T);
     }
     cp /= rho;
 
     scalar dT = 0;
     for (label i = 0; i < nSpecie_; i++)
     {
-        const scalar hi = specieThermo_[i].ha(p, T);
+        const scalar hi = specieThermos_[i].ha(p, T);
         dT += hi*dcdt[i];
     }
     dT /= rho*cp;
@@ -228,8 +228,8 @@ void Foam::StandardChemistryModel<ReactionThermo, ThermoType>::jacobian
     scalarField cpi(nSpecie_);
     for (label i = 0; i < nSpecie_; i++)
     {
-        hi[i] = specieThermo_[i].ha(p, T);
-        cpi[i] = specieThermo_[i].cp(p, T);
+        hi[i] = specieThermos_[i].ha(p, T);
+        cpi[i] = specieThermos_[i].cp(p, T);
     }
     scalar omegaI = 0;
     List<label> dummy;
@@ -248,7 +248,7 @@ void Foam::StandardChemistryModel<ReactionThermo, ThermoType>::jacobian
     for (label i=0; i<nSpecie_; i++)
     {
         cpMean += c_[i]*cpi[i]; // J/(m^3 K)
-        dcpdTMean += c_[i]*specieThermo_[i].dcpdT(p, T);
+        dcpdTMean += c_[i]*specieThermos_[i].dcpdT(p, T);
     }
     scalar dTdt = 0.0;
     for (label i=0; i<nSpecie_; i++)
@@ -320,7 +320,7 @@ Foam::StandardChemistryModel<ReactionThermo, ThermoType>::tc() const
 
             for (label i=0; i<nSpecie_; i++)
             {
-                c_[i] = rhoi*Y_[i][celli]/specieThermo_[i].W();
+                c_[i] = rhoi*Y_[i][celli]/specieThermos_[i].W();
                 cSum += c_[i];
             }
 
@@ -368,7 +368,7 @@ Foam::StandardChemistryModel<ReactionThermo, ThermoType>::Qdot() const
         {
             forAll(Qdot, celli)
             {
-                const scalar hi = specieThermo_[i].Hf();
+                const scalar hi = specieThermos_[i].Hf();
                 Qdot[celli] -= hi*RR_[i][celli];
             }
         }
@@ -416,7 +416,7 @@ Foam::StandardChemistryModel<ReactionThermo, ThermoType>::calculateRR
         for (label i=0; i<nSpecie_; i++)
         {
             const scalar Yi = Y_[i][celli];
-            c_[i] = rhoi*Yi/specieThermo_[i].W();
+            c_[i] = rhoi*Yi/specieThermos_[i].W();
         }
 
         const Reaction<ThermoType>& R = reactions_[ri];
@@ -441,7 +441,7 @@ Foam::StandardChemistryModel<ReactionThermo, ThermoType>::calculateRR
             }
         }
 
-        RR[celli] *= specieThermo_[si].W();
+        RR[celli] *= specieThermos_[si].W();
     }
 
     return tRR;
@@ -471,14 +471,14 @@ void Foam::StandardChemistryModel<ReactionThermo, ThermoType>::calculate()
         for (label i=0; i<nSpecie_; i++)
         {
             const scalar Yi = Y_[i][celli];
-            c_[i] = rhoi*Yi/specieThermo_[i].W();
+            c_[i] = rhoi*Yi/specieThermos_[i].W();
         }
 
         omega(pi, Ti, c_, celli, dcdt_);
 
         for (label i=0; i<nSpecie_; i++)
         {
-            RR_[i][celli] = dcdt_[i]*specieThermo_[i].W();
+            RR_[i][celli] = dcdt_[i]*specieThermos_[i].W();
         }
     }
 }
@@ -519,7 +519,7 @@ Foam::scalar Foam::StandardChemistryModel<ReactionThermo, ThermoType>::solve
 
             for (label i=0; i<nSpecie_; i++)
             {
-                c_[i] = rhoi*Y_[i][celli]/specieThermo_[i].W();
+                c_[i] = rhoi*Y_[i][celli]/specieThermos_[i].W();
                 c0[i] = c_[i];
             }
 
@@ -542,7 +542,7 @@ Foam::scalar Foam::StandardChemistryModel<ReactionThermo, ThermoType>::solve
             for (label i=0; i<nSpecie_; i++)
             {
                 RR_[i][celli] =
-                    (c_[i] - c0[i])*specieThermo_[i].W()/deltaT[celli];
+                    (c_[i] - c0[i])*specieThermos_[i].W()/deltaT[celli];
             }
         }
         else
diff --git a/src/thermophysicalModels/chemistryModel/chemistryModel/StandardChemistryModel/StandardChemistryModel.H b/src/thermophysicalModels/chemistryModel/chemistryModel/StandardChemistryModel/StandardChemistryModel.H
index efbb25f89b..0c9d8214f9 100644
--- a/src/thermophysicalModels/chemistryModel/chemistryModel/StandardChemistryModel/StandardChemistryModel.H
+++ b/src/thermophysicalModels/chemistryModel/chemistryModel/StandardChemistryModel/StandardChemistryModel.H
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2019 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2020 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -80,7 +80,7 @@ protected:
         const PtrList<volScalarField>& Y_;
 
         //- Thermodynamic data of the species
-        const PtrList<ThermoType>& specieThermo_;
+        const PtrList<ThermoType>& specieThermos_;
 
         //- Reactions
         const ReactionList<ThermoType> reactions_;
@@ -136,7 +136,7 @@ public:
         inline const PtrList<Reaction<ThermoType>>& reactions() const;
 
         //- Thermodynamic data of the species
-        inline const PtrList<ThermoType>& specieThermo() const;
+        inline const PtrList<ThermoType>& specieThermos() const;
 
         //- The number of species
         virtual inline label nSpecie() const;
diff --git a/src/thermophysicalModels/chemistryModel/chemistryModel/StandardChemistryModel/StandardChemistryModelI.H b/src/thermophysicalModels/chemistryModel/chemistryModel/StandardChemistryModel/StandardChemistryModelI.H
index aca73fb46e..42916c7c6b 100644
--- a/src/thermophysicalModels/chemistryModel/chemistryModel/StandardChemistryModel/StandardChemistryModelI.H
+++ b/src/thermophysicalModels/chemistryModel/chemistryModel/StandardChemistryModel/StandardChemistryModelI.H
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2018 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2020 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -55,9 +55,9 @@ Foam::StandardChemistryModel<ReactionThermo, ThermoType>::reactions() const
 
 template<class ReactionThermo, class ThermoType>
 inline const Foam::PtrList<ThermoType>&
-Foam::StandardChemistryModel<ReactionThermo, ThermoType>::specieThermo() const
+Foam::StandardChemistryModel<ReactionThermo, ThermoType>::specieThermos() const
 {
-    return specieThermo_;
+    return specieThermos_;
 }
 
 
diff --git a/src/thermophysicalModels/chemistryModel/chemistryModel/TDACChemistryModel/TDACChemistryModel.C b/src/thermophysicalModels/chemistryModel/chemistryModel/TDACChemistryModel/TDACChemistryModel.C
index cb8b4f5d84..6956974997 100644
--- a/src/thermophysicalModels/chemistryModel/chemistryModel/TDACChemistryModel/TDACChemistryModel.C
+++ b/src/thermophysicalModels/chemistryModel/chemistryModel/TDACChemistryModel/TDACChemistryModel.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2016-2019 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2016-2020 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -351,7 +351,7 @@ void Foam::TDACChemistryModel<ReactionThermo, ThermoType>::derivatives
     scalar rho = 0;
     for (label i=0; i<this->c_.size(); i++)
     {
-        const scalar W = this->specieThermo_[i].W();
+        const scalar W = this->specieThermos_[i].W();
         rho += W*this->c_[i];
     }
 
@@ -359,7 +359,7 @@ void Foam::TDACChemistryModel<ReactionThermo, ThermoType>::derivatives
     for (label i=0; i<this->c_.size(); i++)
     {
         // cp function returns [J/kmol/K]
-        cp += this->c_[i]*this->specieThermo_[i].cp(p, T);
+        cp += this->c_[i]*this->specieThermos_[i].cp(p, T);
     }
     cp /= rho;
 
@@ -380,7 +380,7 @@ void Foam::TDACChemistryModel<ReactionThermo, ThermoType>::derivatives
         }
 
         // ha function returns [J/kmol]
-        const scalar hi = this->specieThermo_[si].ha(p, T);
+        const scalar hi = this->specieThermos_[si].ha(p, T);
         dT += hi*dcdt[i];
     }
     dT /= rho*cp;
@@ -434,8 +434,8 @@ void Foam::TDACChemistryModel<ReactionThermo, ThermoType>::jacobian
     scalarField cpi(this->c_.size());
     forAll(hi, i)
     {
-        hi[i] = this->specieThermo_[i].ha(p, T);
-        cpi[i] = this->specieThermo_[i].cp(p, T);
+        hi[i] = this->specieThermos_[i].ha(p, T);
+        cpi[i] = this->specieThermos_[i].cp(p, T);
     }
 
     scalar omegaI = 0;
@@ -485,7 +485,7 @@ void Foam::TDACChemistryModel<ReactionThermo, ThermoType>::jacobian
     {
         cpMean += this->c_[i]*cpi[i]; // J/(m^3 K)
         // Already multiplied by rho
-        dcpdTMean += this->c_[i]*this->specieThermo_[i].dcpdT(p, T);
+        dcpdTMean += this->c_[i]*this->specieThermos_[i].dcpdT(p, T);
     }
 
     scalar dTdt = 0;
@@ -608,7 +608,7 @@ Foam::scalar Foam::TDACChemistryModel<ReactionThermo, ThermoType>::solve
 
         for (label i=0; i<this->nSpecie_; i++)
         {
-            c[i] = rhoi*this->Y_[i][celli]/this->specieThermo_[i].W();
+            c[i] = rhoi*this->Y_[i][celli]/this->specieThermos_[i].W();
             c0[i] = c[i];
             phiq[i] = this->Y()[i][celli];
         }
@@ -636,7 +636,7 @@ Foam::scalar Foam::TDACChemistryModel<ReactionThermo, ThermoType>::solve
             // Retrieved solution stored in Rphiq
             for (label i=0; i<this->nSpecie(); i++)
             {
-                c[i] = rhoi*Rphiq[i]/this->specieThermo_[i].W();
+                c[i] = rhoi*Rphiq[i]/this->specieThermos_[i].W();
             }
 
             searchISATCpuTime_ += clockTime_.timeIncrement();
@@ -702,7 +702,7 @@ Foam::scalar Foam::TDACChemistryModel<ReactionThermo, ThermoType>::solve
             {
                 forAll(c, i)
                 {
-                    Rphiq[i] = c[i]/rhoi*this->specieThermo_[i].W();
+                    Rphiq[i] = c[i]/rhoi*this->specieThermos_[i].W();
                 }
                 if (tabulation_->variableTimeStep())
                 {
@@ -746,7 +746,7 @@ Foam::scalar Foam::TDACChemistryModel<ReactionThermo, ThermoType>::solve
         for (label i=0; i<this->nSpecie_; i++)
         {
             this->RR_[i][celli] =
-                (c[i] - c0[i])*this->specieThermo_[i].W()/deltaT[celli];
+                (c[i] - c0[i])*this->specieThermos_[i].W()/deltaT[celli];
         }
     }
 
diff --git a/src/thermophysicalModels/chemistryModel/chemistryModel/TDACChemistryModel/reduction/DAC/DAC.C b/src/thermophysicalModels/chemistryModel/chemistryModel/TDACChemistryModel/reduction/DAC/DAC.C
index 94e6d5647e..36213b28a2 100644
--- a/src/thermophysicalModels/chemistryModel/chemistryModel/TDACChemistryModel/reduction/DAC/DAC.C
+++ b/src/thermophysicalModels/chemistryModel/chemistryModel/TDACChemistryModel/reduction/DAC/DAC.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2016-2019 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2016-2020 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -238,7 +238,7 @@ Foam::chemistryReductionMethods::DAC<CompType, ThermoType>::DAC
                 }
             }
             scalar curMm =
-                this->chemistry_.specieThermo()[fuelSpeciesID_[i]].W();
+                this->chemistry_.specieThermos()[fuelSpeciesID_[i]].W();
             Mmtot += fuelSpeciesProp_[i]/curMm;
         }
 
@@ -248,7 +248,7 @@ Foam::chemistryReductionMethods::DAC<CompType, ThermoType>::DAC
         forAll(fuelSpecies_, i)
         {
             label curID = fuelSpeciesID_[i];
-            scalar curMm = this->chemistry_.specieThermo()[curID].W();
+            scalar curMm = this->chemistry_.specieThermos()[curID].W();
 
             nbC += fuelSpeciesProp_[i]*Mmtot/curMm*sC_[curID];
             nbO += fuelSpeciesProp_[i]*Mmtot/curMm*sO_[curID];
diff --git a/src/thermophysicalModels/chemistryModel/chemistryModel/TDACChemistryModel/tabulation/ISAT/ISAT.C b/src/thermophysicalModels/chemistryModel/chemistryModel/TDACChemistryModel/tabulation/ISAT/ISAT.C
index 825d3c06bb..39cfce5a8c 100644
--- a/src/thermophysicalModels/chemistryModel/chemistryModel/TDACChemistryModel/tabulation/ISAT/ISAT.C
+++ b/src/thermophysicalModels/chemistryModel/chemistryModel/TDACChemistryModel/tabulation/ISAT/ISAT.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2016-2019 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2016-2020 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -353,7 +353,7 @@ void Foam::chemistryTabulationMethods::ISAT<CompType, ThermoType>::computeA
         {
             s2c = this->chemistry_.simplifiedToCompleteIndex()[i];
         }
-        Rcq[i] = rhoi*Rphiq[s2c]/this->chemistry_.specieThermo()[s2c].W();
+        Rcq[i] = rhoi*Rphiq[s2c]/this->chemistry_.specieThermos()[s2c].W();
     }
     Rcq[speciesNumber] = Rphiq[Rphiq.size() - nAdditionalEqns_];
     Rcq[speciesNumber + 1] = Rphiq[Rphiq.size() - nAdditionalEqns_ + 1];
@@ -393,16 +393,16 @@ void Foam::chemistryTabulationMethods::ISAT<CompType, ThermoType>::computeA
                 sj = this->chemistry_.simplifiedToCompleteIndex()[j];
             }
             A(i, j) *=
-              -dt*this->chemistry_.specieThermo()[si].W()
-               /this->chemistry_.specieThermo()[sj].W();
+              -dt*this->chemistry_.specieThermos()[si].W()
+               /this->chemistry_.specieThermos()[sj].W();
         }
 
         A(i, i) += 1;
         // Columns for pressure and temperature
         A(i, speciesNumber) *=
-            -dt*this->chemistry_.specieThermo()[si].W()/rhoi;
+            -dt*this->chemistry_.specieThermos()[si].W()/rhoi;
         A(i, speciesNumber + 1) *=
-            -dt*this->chemistry_.specieThermo()[si].W()/rhoi;
+            -dt*this->chemistry_.specieThermos()[si].W()/rhoi;
     }
 
     // For the temperature and pressure lines, ddc(dTdt)
@@ -416,9 +416,9 @@ void Foam::chemistryTabulationMethods::ISAT<CompType, ThermoType>::computeA
         }
 
         A(speciesNumber, i) *=
-            -dt*rhoi/this->chemistry_.specieThermo()[si].W();
+            -dt*rhoi/this->chemistry_.specieThermos()[si].W();
         A(speciesNumber + 1, i) *=
-            -dt*rhoi/this->chemistry_.specieThermo()[si].W();
+            -dt*rhoi/this->chemistry_.specieThermos()[si].W();
     }
 
     A(speciesNumber, speciesNumber) = -dt*A(speciesNumber, speciesNumber) + 1;
diff --git a/src/thermophysicalModels/chemistryModel/chemistrySolver/EulerImplicit/EulerImplicit.C b/src/thermophysicalModels/chemistryModel/chemistrySolver/EulerImplicit/EulerImplicit.C
index 90a34faa4a..aab1ae27c8 100644
--- a/src/thermophysicalModels/chemistryModel/chemistrySolver/EulerImplicit/EulerImplicit.C
+++ b/src/thermophysicalModels/chemistryModel/chemistrySolver/EulerImplicit/EulerImplicit.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2019 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2020 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -111,11 +111,11 @@ void Foam::EulerImplicit<ChemistryModel>::solve
     const scalar cTot = sum(c);
     typename ChemistryModel::thermoType mixture
     (
-        (this->specieThermo_[0].W()*c[0])*this->specieThermo_[0]
+        (this->specieThermos_[0].W()*c[0])*this->specieThermos_[0]
     );
     for (label i=1; i<nSpecie; i++)
     {
-        mixture += (this->specieThermo_[i].W()*c[i])*this->specieThermo_[i];
+        mixture += (this->specieThermos_[i].W()*c[i])*this->specieThermos_[i];
     }
     const scalar ha = mixture.Ha(p, T);
     const scalar deltaTEst = min(deltaT, subDeltaT);
@@ -189,10 +189,10 @@ void Foam::EulerImplicit<ChemistryModel>::solve
     }
 
     // Update the temperature
-    mixture = (this->specieThermo_[0].W()*c[0])*this->specieThermo_[0];
+    mixture = (this->specieThermos_[0].W()*c[0])*this->specieThermos_[0];
     for (label i=1; i<nSpecie; i++)
     {
-        mixture += (this->specieThermo_[i].W()*c[i])*this->specieThermo_[i];
+        mixture += (this->specieThermos_[i].W()*c[i])*this->specieThermos_[i];
     }
     T = mixture.THa(ha, p, T);
 }
diff --git a/src/thermophysicalModels/reactionThermo/Make/files b/src/thermophysicalModels/reactionThermo/Make/files
index 9effbea6e6..2be3ae07f3 100644
--- a/src/thermophysicalModels/reactionThermo/Make/files
+++ b/src/thermophysicalModels/reactionThermo/Make/files
@@ -1,4 +1,3 @@
-mixtures/basicMultiComponentMixture/basicMultiComponentMixture.C
 mixtures/basicSpecieMixture/basicSpecieMixture.C
 mixtures/basicCombustionMixture/basicCombustionMixture.C
 
diff --git a/src/thermophysicalModels/reactionThermo/makeReactionThermo.H b/src/thermophysicalModels/reactionThermo/makeReactionThermo.H
index ff9ac6050f..c461b47729 100644
--- a/src/thermophysicalModels/reactionThermo/makeReactionThermo.H
+++ b/src/thermophysicalModels/reactionThermo/makeReactionThermo.H
@@ -28,7 +28,6 @@ License
 
 #include "makeThermo.H"
 #include "SpecieMixture.H"
-#include "addToRunTimeSelectionTable.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
diff --git a/src/thermophysicalModels/reactionThermo/mixtures/SpecieMixture/SpecieMixture.H b/src/thermophysicalModels/reactionThermo/mixtures/SpecieMixture/SpecieMixture.H
index abe68fd3dd..afcc953a78 100644
--- a/src/thermophysicalModels/reactionThermo/mixtures/SpecieMixture/SpecieMixture.H
+++ b/src/thermophysicalModels/reactionThermo/mixtures/SpecieMixture/SpecieMixture.H
@@ -104,7 +104,7 @@ public:
 
     // Member Functions
 
-        // Per specie properties
+        // Specie properties
 
             //- Molecular weight of the given specie [kg/kmol]
             virtual scalar Wi(const label speciei) const;
@@ -112,9 +112,6 @@ public:
             //- Enthalpy of formation [J/kg]
             virtual scalar Hf(const label speciei) const;
 
-
-        // Per specie thermo properties
-
             //- Density [kg/m^3]
             virtual scalar rho
             (
diff --git a/src/thermophysicalModels/reactionThermo/mixtures/basicCombustionMixture/basicCombustionMixture.C b/src/thermophysicalModels/reactionThermo/mixtures/basicCombustionMixture/basicCombustionMixture.C
index 68f43c53ce..4a072ab200 100644
--- a/src/thermophysicalModels/reactionThermo/mixtures/basicCombustionMixture/basicCombustionMixture.C
+++ b/src/thermophysicalModels/reactionThermo/mixtures/basicCombustionMixture/basicCombustionMixture.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2014-2018 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2014-2020 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -43,8 +43,30 @@ Foam::basicCombustionMixture::basicCombustionMixture
     const word& phaseName
 )
 :
-    basicSpecieMixture(thermoDict, specieNames, mesh, phaseName)
-{}
+    basicMixture(thermoDict, mesh, phaseName),
+    species_(specieNames),
+    Y_(species_.size())
+{
+    forAll(species_, i)
+    {
+        Y_.set
+        (
+            i,
+            new volScalarField
+            (
+                IOobject
+                (
+                    IOobject::groupName(species_[i], phaseName),
+                    mesh.time().timeName(),
+                    mesh,
+                    IOobject::MUST_READ,
+                    IOobject::AUTO_WRITE
+                ),
+                mesh
+            )
+        );
+    }
+}
 
 
 // ************************************************************************* //
diff --git a/src/thermophysicalModels/reactionThermo/mixtures/basicCombustionMixture/basicCombustionMixture.H b/src/thermophysicalModels/reactionThermo/mixtures/basicCombustionMixture/basicCombustionMixture.H
index 14478c65ad..284c9c58a5 100644
--- a/src/thermophysicalModels/reactionThermo/mixtures/basicCombustionMixture/basicCombustionMixture.H
+++ b/src/thermophysicalModels/reactionThermo/mixtures/basicCombustionMixture/basicCombustionMixture.H
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2014-2019 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2014-2020 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -25,7 +25,7 @@ Class
     Foam::basicCombustionMixture
 
 Description
-    Specialization of the basicSpecieMixture for combustion.
+    Specialization of the basicMixture for combustion.
 
 SourceFiles
     basicCombustionMixture.C
@@ -35,7 +35,10 @@ SourceFiles
 #ifndef basicCombustionMixture_H
 #define basicCombustionMixture_H
 
-#include "basicSpecieMixture.H"
+#include "volFields.H"
+#include "PtrList.H"
+#include "basicMixture.H"
+#include "speciesTable.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -48,9 +51,20 @@ namespace Foam
 
 class basicCombustionMixture
 :
-    public basicSpecieMixture
+    public basicMixture
 {
 
+protected:
+
+    // Protected data
+
+        //- Table of specie names
+        speciesTable species_;
+
+        //- Species mass fractions
+        PtrList<volScalarField> Y_;
+
+
 public:
 
     //- Run time type information
@@ -80,6 +94,15 @@ public:
 
     // Member Functions
 
+        //- Does the mixture include this specie?
+        inline bool contains(const word& specieName) const;
+
+        //- Return the mass-fraction field for a specie given by name
+        inline volScalarField& Y(const word& specieName);
+
+        //- Return the const mass-fraction field for a specie given by name
+        inline const volScalarField& Y(const word& specieName) const;
+
         inline scalar fres(const scalar ft, const scalar stoicRatio) const;
 
         inline tmp<volScalarField> fres
diff --git a/src/thermophysicalModels/reactionThermo/mixtures/basicCombustionMixture/basicCombustionMixtureI.H b/src/thermophysicalModels/reactionThermo/mixtures/basicCombustionMixture/basicCombustionMixtureI.H
index bfbffe68dc..00f61941fb 100644
--- a/src/thermophysicalModels/reactionThermo/mixtures/basicCombustionMixture/basicCombustionMixtureI.H
+++ b/src/thermophysicalModels/reactionThermo/mixtures/basicCombustionMixture/basicCombustionMixtureI.H
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2014-2018 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2014-2020 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -23,6 +23,33 @@ License
 
 \*---------------------------------------------------------------------------*/
 
+inline bool Foam::basicCombustionMixture::contains
+(
+    const word& specieName
+) const
+{
+    return species_.found(specieName);
+}
+
+
+inline Foam::volScalarField& Foam::basicCombustionMixture::Y
+(
+    const word& specieName
+)
+{
+    return Y_[species_[specieName]];
+}
+
+
+inline const Foam::volScalarField& Foam::basicCombustionMixture::Y
+(
+    const word& specieName
+) const
+{
+    return Y_[species_[specieName]];
+}
+
+
 inline Foam::scalar Foam::basicCombustionMixture::fres
 (
     const scalar ft,
diff --git a/src/thermophysicalModels/reactionThermo/mixtures/basicMultiComponentMixture/basicMultiComponentMixture.C b/src/thermophysicalModels/reactionThermo/mixtures/basicMultiComponentMixture/basicMultiComponentMixture.C
deleted file mode 100644
index cb6f02c7ee..0000000000
--- a/src/thermophysicalModels/reactionThermo/mixtures/basicMultiComponentMixture/basicMultiComponentMixture.C
+++ /dev/null
@@ -1,154 +0,0 @@
-/*---------------------------------------------------------------------------*\
-  =========                 |
-  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
-   \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2018 OpenFOAM Foundation
-     \\/     M anipulation  |
--------------------------------------------------------------------------------
-License
-    This file is part of OpenFOAM.
-
-    OpenFOAM is free software: you can redistribute it and/or modify it
-    under the terms of the GNU General Public License as published by
-    the Free Software Foundation, either version 3 of the License, or
-    (at your option) any later version.
-
-    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
-    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
-    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
-    for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
-
-\*---------------------------------------------------------------------------*/
-
-#include "basicMultiComponentMixture.H"
-
-// * * * * * * * * * * * * * Static Member Functions * * * * * * * * * * * * //
-
-namespace Foam
-{
-    defineTypeNameAndDebug(basicMultiComponentMixture, 0);
-}
-
-// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
-
-Foam::basicMultiComponentMixture::basicMultiComponentMixture
-(
-    const dictionary& thermoDict,
-    const wordList& specieNames,
-    const fvMesh& mesh,
-    const word& phaseName
-)
-:
-    basicMixture(thermoDict, mesh, phaseName),
-    species_(specieNames),
-    active_(species_.size(), true),
-    Y_(species_.size())
-{
-    tmp<volScalarField> tYdefault;
-
-    forAll(species_, i)
-    {
-        IOobject header
-        (
-            IOobject::groupName(species_[i], phaseName),
-            mesh.time().timeName(),
-            mesh,
-            IOobject::NO_READ
-        );
-
-        // check if field exists and can be read
-        if (header.typeHeaderOk<volScalarField>(true))
-        {
-            Y_.set
-            (
-                i,
-                new volScalarField
-                (
-                    IOobject
-                    (
-                        IOobject::groupName(species_[i], phaseName),
-                        mesh.time().timeName(),
-                        mesh,
-                        IOobject::MUST_READ,
-                        IOobject::AUTO_WRITE
-                    ),
-                    mesh
-                )
-            );
-        }
-        else
-        {
-            // Read Ydefault if not already read
-            if (!tYdefault.valid())
-            {
-                word YdefaultName(IOobject::groupName("Ydefault", phaseName));
-
-                IOobject timeIO
-                (
-                    YdefaultName,
-                    mesh.time().timeName(),
-                    mesh,
-                    IOobject::MUST_READ,
-                    IOobject::NO_WRITE
-                );
-
-                IOobject constantIO
-                (
-                    YdefaultName,
-                    mesh.time().constant(),
-                    mesh,
-                    IOobject::MUST_READ,
-                    IOobject::NO_WRITE
-                );
-
-                IOobject time0IO
-                (
-                    YdefaultName,
-                    Time::timeName(0),
-                    mesh,
-                    IOobject::MUST_READ,
-                    IOobject::NO_WRITE
-                );
-
-                if (timeIO.typeHeaderOk<volScalarField>(true))
-                {
-                    tYdefault = new volScalarField(timeIO, mesh);
-                }
-                else if (constantIO.typeHeaderOk<volScalarField>(true))
-                {
-                    tYdefault = new volScalarField(constantIO, mesh);
-                }
-                else
-                {
-                    tYdefault = new volScalarField(time0IO, mesh);
-                }
-            }
-
-            Y_.set
-            (
-                i,
-                new volScalarField
-                (
-                    IOobject
-                    (
-                        IOobject::groupName(species_[i], phaseName),
-                        mesh.time().timeName(),
-                        mesh,
-                        IOobject::NO_READ,
-                        IOobject::AUTO_WRITE
-                    ),
-                    tYdefault()
-                )
-            );
-        }
-    }
-
-    // Do not enforce constraint of sum of mass fractions to equal 1 here
-    // - not applicable to all models
-}
-
-
-// ************************************************************************* //
diff --git a/src/thermophysicalModels/reactionThermo/mixtures/basicMultiComponentMixture/basicMultiComponentMixture.H b/src/thermophysicalModels/reactionThermo/mixtures/basicMultiComponentMixture/basicMultiComponentMixture.H
deleted file mode 100644
index 1fcf71d5ba..0000000000
--- a/src/thermophysicalModels/reactionThermo/mixtures/basicMultiComponentMixture/basicMultiComponentMixture.H
+++ /dev/null
@@ -1,154 +0,0 @@
-/*---------------------------------------------------------------------------*\
-  =========                 |
-  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
-   \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2019 OpenFOAM Foundation
-     \\/     M anipulation  |
--------------------------------------------------------------------------------
-License
-    This file is part of OpenFOAM.
-
-    OpenFOAM is free software: you can redistribute it and/or modify it
-    under the terms of the GNU General Public License as published by
-    the Free Software Foundation, either version 3 of the License, or
-    (at your option) any later version.
-
-    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
-    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
-    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
-    for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
-
-Class
-    Foam::basicMultiComponentMixture
-
-Description
-    Multi-component mixture.
-
-    Provides a list of mass fraction fields and helper functions to
-    query mixture composition.
-
-SourceFiles
-    basicMultiComponentMixture.C
-
-\*---------------------------------------------------------------------------*/
-
-#ifndef basicMultiComponentMixture_H
-#define basicMultiComponentMixture_H
-
-#include "volFields.H"
-#include "PtrList.H"
-#include "basicMixture.H"
-#include "speciesTable.H"
-#include "typeInfo.H"
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-namespace Foam
-{
-
-/*---------------------------------------------------------------------------*\
-                 Class basicMultiComponentMixture Declaration
-\*---------------------------------------------------------------------------*/
-
-class basicMultiComponentMixture
-:
-    public basicMixture
-{
-
-protected:
-
-    // Protected data
-
-        //- Table of specie names
-        speciesTable species_;
-
-        //- List of specie active flags
-        mutable List<bool> active_;
-
-        //- Species mass fractions
-        PtrList<volScalarField> Y_;
-
-
-public:
-
-    //- Run time type information
-    TypeName("basicMultiComponentMixture");
-
-
-    //- The base class of the mixture
-    typedef basicMultiComponentMixture basicMixtureType;
-
-
-    // Constructors
-
-        //- Construct from dictionary, species names, mesh and phase name
-        basicMultiComponentMixture
-        (
-            const dictionary&,
-            const wordList& specieNames,
-            const fvMesh&,
-            const word&
-        );
-
-
-    //- Destructor
-    virtual ~basicMultiComponentMixture()
-    {}
-
-
-    // Member Functions
-
-        //- Return the table of species
-        inline const speciesTable& species() const;
-
-        //- Does the mixture include this specie?
-        inline bool contains(const word& specieName) const;
-
-        //- Return true for active species
-        inline bool active(label speciei) const;
-
-        //- Return the bool list of active species
-        inline const List<bool>& active() const;
-
-        //- Set speciei active
-        inline void setActive(label speciei) const;
-
-        //- Set speciei inactive
-        inline void setInactive(label speciei) const;
-
-        //- Return the mass-fraction fields
-        inline PtrList<volScalarField>& Y();
-
-        //- Return the const mass-fraction fields
-        inline const PtrList<volScalarField>& Y() const;
-
-        //- Return the mass-fraction field for a specie given by index
-        inline volScalarField& Y(const label i);
-
-        //- Return the const mass-fraction field for a specie given by index
-        inline const volScalarField& Y(const label i) const;
-
-        //- Return the mass-fraction field for a specie given by name
-        inline volScalarField& Y(const word& specieName);
-
-        //- Return the const mass-fraction field for a specie given by name
-        inline const volScalarField& Y(const word& specieName) const;
-};
-
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-} // End namespace Foam
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-#include "basicMultiComponentMixtureI.H"
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-#endif
-
-// ************************************************************************* //
diff --git a/src/thermophysicalModels/reactionThermo/mixtures/basicSpecieMixture/basicSpecieMixture.C b/src/thermophysicalModels/reactionThermo/mixtures/basicSpecieMixture/basicSpecieMixture.C
index 047dbfed2a..e5dca750b9 100644
--- a/src/thermophysicalModels/reactionThermo/mixtures/basicSpecieMixture/basicSpecieMixture.C
+++ b/src/thermophysicalModels/reactionThermo/mixtures/basicSpecieMixture/basicSpecieMixture.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2014-2018 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2014-2020 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -43,8 +43,113 @@ Foam::basicSpecieMixture::basicSpecieMixture
     const word& phaseName
 )
 :
-    basicMultiComponentMixture(thermoDict, specieNames, mesh, phaseName)
-{}
+    basicMixture(thermoDict, mesh, phaseName),
+    species_(specieNames),
+    active_(species_.size(), true),
+    Y_(species_.size())
+{
+    tmp<volScalarField> tYdefault;
+
+    forAll(species_, i)
+    {
+        IOobject header
+        (
+            IOobject::groupName(species_[i], phaseName),
+            mesh.time().timeName(),
+            mesh,
+            IOobject::NO_READ
+        );
+
+        // check if field exists and can be read
+        if (header.typeHeaderOk<volScalarField>(true))
+        {
+            Y_.set
+            (
+                i,
+                new volScalarField
+                (
+                    IOobject
+                    (
+                        IOobject::groupName(species_[i], phaseName),
+                        mesh.time().timeName(),
+                        mesh,
+                        IOobject::MUST_READ,
+                        IOobject::AUTO_WRITE
+                    ),
+                    mesh
+                )
+            );
+        }
+        else
+        {
+            // Read Ydefault if not already read
+            if (!tYdefault.valid())
+            {
+                word YdefaultName(IOobject::groupName("Ydefault", phaseName));
+
+                IOobject timeIO
+                (
+                    YdefaultName,
+                    mesh.time().timeName(),
+                    mesh,
+                    IOobject::MUST_READ,
+                    IOobject::NO_WRITE
+                );
+
+                IOobject constantIO
+                (
+                    YdefaultName,
+                    mesh.time().constant(),
+                    mesh,
+                    IOobject::MUST_READ,
+                    IOobject::NO_WRITE
+                );
+
+                IOobject time0IO
+                (
+                    YdefaultName,
+                    Time::timeName(0),
+                    mesh,
+                    IOobject::MUST_READ,
+                    IOobject::NO_WRITE
+                );
+
+                if (timeIO.typeHeaderOk<volScalarField>(true))
+                {
+                    tYdefault = new volScalarField(timeIO, mesh);
+                }
+                else if (constantIO.typeHeaderOk<volScalarField>(true))
+                {
+                    tYdefault = new volScalarField(constantIO, mesh);
+                }
+                else
+                {
+                    tYdefault = new volScalarField(time0IO, mesh);
+                }
+            }
+
+            Y_.set
+            (
+                i,
+                new volScalarField
+                (
+                    IOobject
+                    (
+                        IOobject::groupName(species_[i], phaseName),
+                        mesh.time().timeName(),
+                        mesh,
+                        IOobject::NO_READ,
+                        IOobject::AUTO_WRITE
+                    ),
+                    tYdefault()
+                )
+            );
+        }
+    }
+
+    // Do not enforce constraint of sum of mass fractions to equal 1 here
+    // - not applicable to all models
+}
 
 
 // ************************************************************************* //
diff --git a/src/thermophysicalModels/reactionThermo/mixtures/basicSpecieMixture/basicSpecieMixture.H b/src/thermophysicalModels/reactionThermo/mixtures/basicSpecieMixture/basicSpecieMixture.H
index 882da89b0a..fac8673933 100644
--- a/src/thermophysicalModels/reactionThermo/mixtures/basicSpecieMixture/basicSpecieMixture.H
+++ b/src/thermophysicalModels/reactionThermo/mixtures/basicSpecieMixture/basicSpecieMixture.H
@@ -25,8 +25,8 @@ Class
     Foam::basicSpecieMixture
 
 Description
-    Specialization of basicMultiComponentMixture for a mixture consisting
-    of a number for molecular species.
+    Specialization of basicMixture for a mixture consisting of a number for
+    molecular species.
 
 SourceFiles
     basicSpecieMixture.C
@@ -36,7 +36,10 @@ SourceFiles
 #ifndef basicSpecieMixture_H
 #define basicSpecieMixture_H
 
-#include "basicMultiComponentMixture.H"
+#include "volFields.H"
+#include "PtrList.H"
+#include "basicMixture.H"
+#include "speciesTable.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -49,9 +52,23 @@ namespace Foam
 
 class basicSpecieMixture
 :
-    public basicMultiComponentMixture
+    public basicMixture
 {
 
+protected:
+
+    // Protected data
+
+        //- Table of specie names
+        speciesTable species_;
+
+        //- List of specie active flags
+        mutable List<bool> active_;
+
+        //- Species mass fractions
+        PtrList<volScalarField> Y_;
+
+
 public:
 
     //- Run time type information
@@ -80,7 +97,44 @@ public:
 
     // Member Functions
 
-        // Per specie properties
+        //- Return the table of species
+        inline const speciesTable& species() const;
+
+        //- Does the mixture include this specie?
+        inline bool contains(const word& specieName) const;
+
+        //- Return true for active species
+        inline bool active(label speciei) const;
+
+        //- Return the bool list of active species
+        inline const List<bool>& active() const;
+
+        //- Set speciei active
+        inline void setActive(label speciei) const;
+
+        //- Set speciei inactive
+        inline void setInactive(label speciei) const;
+
+        //- Return the mass-fraction fields
+        inline PtrList<volScalarField>& Y();
+
+        //- Return the const mass-fraction fields
+        inline const PtrList<volScalarField>& Y() const;
+
+        //- Return the mass-fraction field for a specie given by index
+        inline volScalarField& Y(const label i);
+
+        //- Return the const mass-fraction field for a specie given by index
+        inline const volScalarField& Y(const label i) const;
+
+        //- Return the mass-fraction field for a specie given by name
+        inline volScalarField& Y(const word& specieName);
+
+        //- Return the const mass-fraction field for a specie given by name
+        inline const volScalarField& Y(const word& specieName) const;
+
+
+        // Specie properties
 
             //- Molecular weight of the given specie [kg/kmol]
             virtual scalar Wi(const label speciei) const = 0;
@@ -89,7 +143,7 @@ public:
             virtual scalar Hf(const label speciei) const = 0;
 
 
-        // Per specie thermo properties
+        // Specie thermo properties
 
             //- Density [kg/m^3]
             virtual scalar rho
@@ -188,7 +242,7 @@ public:
             ) const = 0;
 
 
-        // Per specie transport properties
+        // Specie transport properties
 
             //- Dynamic viscosity [kg/m/s]
             virtual scalar mu
@@ -246,6 +300,10 @@ public:
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
+#include "basicSpecieMixtureI.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
 #endif
 
 // ************************************************************************* //
diff --git a/src/thermophysicalModels/reactionThermo/mixtures/basicMultiComponentMixture/basicMultiComponentMixtureI.H b/src/thermophysicalModels/reactionThermo/mixtures/basicSpecieMixture/basicSpecieMixtureI.H
similarity index 68%
rename from src/thermophysicalModels/reactionThermo/mixtures/basicMultiComponentMixture/basicMultiComponentMixtureI.H
rename to src/thermophysicalModels/reactionThermo/mixtures/basicSpecieMixture/basicSpecieMixtureI.H
index b091f7428c..2a1441e4d2 100644
--- a/src/thermophysicalModels/reactionThermo/mixtures/basicMultiComponentMixture/basicMultiComponentMixtureI.H
+++ b/src/thermophysicalModels/reactionThermo/mixtures/basicSpecieMixture/basicSpecieMixtureI.H
@@ -23,69 +23,64 @@ License
 
 \*---------------------------------------------------------------------------*/
 
-inline const Foam::speciesTable&
-Foam::basicMultiComponentMixture::species() const
+inline const Foam::speciesTable& Foam::basicSpecieMixture::species() const
 {
     return species_;
 }
 
 
-inline bool Foam::basicMultiComponentMixture::contains
-(
-    const word& specieName
-) const
+inline bool Foam::basicSpecieMixture::contains(const word& specieName) const
 {
     return species_.found(specieName);
 }
 
 
-inline bool Foam::basicMultiComponentMixture::active(label speciei) const
+inline bool Foam::basicSpecieMixture::active(label speciei) const
 {
     return active_[speciei];
 }
 
 
-inline const Foam::List<bool>& Foam::basicMultiComponentMixture::active() const
+inline const Foam::List<bool>& Foam::basicSpecieMixture::active() const
 {
     return active_;
 }
 
 
-inline void Foam::basicMultiComponentMixture::setActive(label speciei) const
+inline void Foam::basicSpecieMixture::setActive(label speciei) const
 {
     active_[speciei] = true;
     const_cast<volScalarField&>(Y_[speciei]).writeOpt() = IOobject::AUTO_WRITE;
 }
 
 
-inline void Foam::basicMultiComponentMixture::setInactive(label speciei) const
+inline void Foam::basicSpecieMixture::setInactive(label speciei) const
 {
     active_[speciei] = false;
     const_cast<volScalarField&>(Y_[speciei]).writeOpt() = IOobject::NO_WRITE;
 }
 
 
-inline Foam::PtrList<Foam::volScalarField>&
-Foam::basicMultiComponentMixture::Y()
+inline Foam::PtrList<Foam::volScalarField>& Foam::basicSpecieMixture::Y()
 {
     return Y_;
 }
 
 
 inline const Foam::PtrList<Foam::volScalarField>&
-Foam::basicMultiComponentMixture::Y() const
+Foam::basicSpecieMixture::Y() const
 {
     return Y_;
 }
 
 
-inline Foam::volScalarField& Foam::basicMultiComponentMixture::Y(const label i)
+inline Foam::volScalarField& Foam::basicSpecieMixture::Y(const label i)
 {
     return Y_[i];
 }
 
 
-inline const Foam::volScalarField& Foam::basicMultiComponentMixture::Y
+inline const Foam::volScalarField& Foam::basicSpecieMixture::Y
 (
     const label i
 ) const
@@ -94,7 +89,7 @@ inline const Foam::volScalarField& Foam::basicMultiComponentMixture::Y
 }
 
 
-inline Foam::volScalarField& Foam::basicMultiComponentMixture::Y
+inline Foam::volScalarField& Foam::basicSpecieMixture::Y
 (
     const word& specieName
 )
@@ -103,7 +98,7 @@ inline Foam::volScalarField& Foam::basicMultiComponentMixture::Y
 }
 
 
-inline const Foam::volScalarField& Foam::basicMultiComponentMixture::Y
+inline const Foam::volScalarField& Foam::basicSpecieMixture::Y
 (
     const word& specieName
 ) const
diff --git a/src/thermophysicalModels/reactionThermo/mixtures/multiComponentMixture/multiComponentMixture.C b/src/thermophysicalModels/reactionThermo/mixtures/multiComponentMixture/multiComponentMixture.C
index 4df6d5facb..432dd7a845 100644
--- a/src/thermophysicalModels/reactionThermo/mixtures/multiComponentMixture/multiComponentMixture.C
+++ b/src/thermophysicalModels/reactionThermo/mixtures/multiComponentMixture/multiComponentMixture.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2019 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2020 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -34,18 +34,18 @@ Foam::multiComponentMixture<ThermoType>::readSpeciesData
     const dictionary& thermoDict
 ) const
 {
-    PtrList<ThermoType> speciesData(species_.size());
+    PtrList<ThermoType> specieThermos(species_.size());
 
     forAll(species_, i)
     {
-        speciesData.set
+        specieThermos.set
         (
             i,
             new ThermoType(thermoDict.subDict(species_[i]))
         );
     }
 
-    return speciesData;
+    return specieThermos;
 }
 
 
@@ -146,10 +146,10 @@ Foam::multiComponentMixture<ThermoType>::multiComponentMixture
         mesh,
         phaseName
     ),
-    speciesData_(readSpeciesData(thermoDict)),
+    specieThermos_(readSpeciesData(thermoDict)),
     speciesComposition_(readSpeciesComposition(thermoDict, species())),
-    mixture_("mixture", speciesData_[0]),
-    mixtureVol_("volMixture", speciesData_[0])
+    mixture_("mixture", specieThermos_[0]),
+    mixtureVol_("volMixture", specieThermos_[0])
 {
     correctMassFractions();
 }
@@ -163,11 +163,11 @@ const ThermoType& Foam::multiComponentMixture<ThermoType>::cellMixture
     const label celli
 ) const
 {
-    mixture_ = Y_[0][celli]*speciesData_[0];
+    mixture_ = Y_[0][celli]*specieThermos_[0];
 
     for (label n=1; n<Y_.size(); n++)
     {
-        mixture_ += Y_[n][celli]*speciesData_[n];
+        mixture_ += Y_[n][celli]*specieThermos_[n];
     }
 
     return mixture_;
@@ -181,11 +181,11 @@ const ThermoType& Foam::multiComponentMixture<ThermoType>::patchFaceMixture
     const label facei
 ) const
 {
-    mixture_ = Y_[0].boundaryField()[patchi][facei]*speciesData_[0];
+    mixture_ = Y_[0].boundaryField()[patchi][facei]*specieThermos_[0];
 
     for (label n=1; n<Y_.size(); n++)
     {
-        mixture_ += Y_[n].boundaryField()[patchi][facei]*speciesData_[n];
+        mixture_ += Y_[n].boundaryField()[patchi][facei]*specieThermos_[n];
     }
 
     return mixture_;
@@ -201,18 +201,18 @@ const ThermoType& Foam::multiComponentMixture<ThermoType>::cellVolMixture
 ) const
 {
     scalar rhoInv = 0.0;
-    forAll(speciesData_, i)
+    forAll(specieThermos_, i)
     {
-        rhoInv += Y_[i][celli]/speciesData_[i].rho(p, T);
+        rhoInv += Y_[i][celli]/specieThermos_[i].rho(p, T);
     }
 
     mixtureVol_ =
-        Y_[0][celli]/speciesData_[0].rho(p, T)/rhoInv*speciesData_[0];
+        Y_[0][celli]/specieThermos_[0].rho(p, T)/rhoInv*specieThermos_[0];
 
     for (label n=1; n<Y_.size(); n++)
     {
         mixtureVol_ +=
-            Y_[n][celli]/speciesData_[n].rho(p, T)/rhoInv*speciesData_[n];
+            Y_[n][celli]/specieThermos_[n].rho(p, T)/rhoInv*specieThermos_[n];
     }
 
     return mixtureVol_;
@@ -230,21 +230,21 @@ patchFaceVolMixture
 ) const
 {
     scalar rhoInv = 0.0;
-    forAll(speciesData_, i)
+    forAll(specieThermos_, i)
     {
         rhoInv +=
-            Y_[i].boundaryField()[patchi][facei]/speciesData_[i].rho(p, T);
+            Y_[i].boundaryField()[patchi][facei]/specieThermos_[i].rho(p, T);
     }
 
     mixtureVol_ =
-        Y_[0].boundaryField()[patchi][facei]/speciesData_[0].rho(p, T)/rhoInv
-      * speciesData_[0];
+        Y_[0].boundaryField()[patchi][facei]/specieThermos_[0].rho(p, T)/rhoInv
+      * specieThermos_[0];
 
     for (label n=1; n<Y_.size(); n++)
     {
         mixtureVol_ +=
-            Y_[n].boundaryField()[patchi][facei]/speciesData_[n].rho(p,T)
-          / rhoInv*speciesData_[n];
+            Y_[n].boundaryField()[patchi][facei]/specieThermos_[n].rho(p,T)
+          / rhoInv*specieThermos_[n];
     }
 
     return mixtureVol_;
@@ -259,7 +259,7 @@ void Foam::multiComponentMixture<ThermoType>::read
 {
     forAll(species_, i)
     {
-        speciesData_[i] = ThermoType(thermoDict.subDict(species_[i]));
+        specieThermos_[i] = ThermoType(thermoDict.subDict(species_[i]));
     }
 }
 
diff --git a/src/thermophysicalModels/reactionThermo/mixtures/multiComponentMixture/multiComponentMixture.H b/src/thermophysicalModels/reactionThermo/mixtures/multiComponentMixture/multiComponentMixture.H
index 7885adbcb4..5e604f2121 100644
--- a/src/thermophysicalModels/reactionThermo/mixtures/multiComponentMixture/multiComponentMixture.H
+++ b/src/thermophysicalModels/reactionThermo/mixtures/multiComponentMixture/multiComponentMixture.H
@@ -55,8 +55,8 @@ class multiComponentMixture
 {
     // Private Data
 
-        //- Species data
-        PtrList<ThermoType> speciesData_;
+        //- List of specie thermo
+        PtrList<ThermoType> specieThermos_;
 
         typedef HashTable<List<specieElement>> speciesCompositionTable;
 
@@ -119,9 +119,9 @@ public:
         }
 
         //- Return the raw specie thermodynamic data
-        const PtrList<ThermoType>& speciesData() const
+        const PtrList<ThermoType>& specieThermos() const
         {
-            return speciesData_;
+            return specieThermos_;
         }
 
         //- Return the table of species composition
@@ -159,7 +159,7 @@ public:
         //- Return thermo based on index
         inline const ThermoType& specieThermo(const label speciei) const
         {
-            return speciesData_[speciei];
+            return specieThermos_[speciei];
         }
 };
 
diff --git a/src/thermophysicalModels/reactionThermo/psiReactionThermo/psiReactionThermo.H b/src/thermophysicalModels/reactionThermo/psiReactionThermo/psiReactionThermo.H
index bb45f16024..18f4182cd0 100644
--- a/src/thermophysicalModels/reactionThermo/psiReactionThermo/psiReactionThermo.H
+++ b/src/thermophysicalModels/reactionThermo/psiReactionThermo/psiReactionThermo.H
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2019 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2020 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -37,8 +37,6 @@ SourceFiles
 
 #include "psiThermo.H"
 #include "basicSpecieMixture.H"
-#include "autoPtr.H"
-#include "runTimeSelectionTables.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
diff --git a/src/thermophysicalModels/reactionThermo/psiuReactionThermo/psiuReactionThermo.C b/src/thermophysicalModels/reactionThermo/psiuReactionThermo/psiuReactionThermo.C
index 8512cb8c84..6f27b4b7a1 100644
--- a/src/thermophysicalModels/reactionThermo/psiuReactionThermo/psiuReactionThermo.C
+++ b/src/thermophysicalModels/reactionThermo/psiuReactionThermo/psiuReactionThermo.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2018 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2020 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -106,7 +106,7 @@ psiuReactionThermo::psiuReactionThermo
     const word& phaseName
 )
 :
-    psiReactionThermo(mesh, phaseName)
+    psiThermo(mesh, phaseName)
 {}
 
 
diff --git a/src/thermophysicalModels/reactionThermo/psiuReactionThermo/psiuReactionThermo.H b/src/thermophysicalModels/reactionThermo/psiuReactionThermo/psiuReactionThermo.H
index f824a3f83e..1a3c02a01d 100644
--- a/src/thermophysicalModels/reactionThermo/psiuReactionThermo/psiuReactionThermo.H
+++ b/src/thermophysicalModels/reactionThermo/psiuReactionThermo/psiuReactionThermo.H
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2019 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2020 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -36,7 +36,8 @@ SourceFiles
 #ifndef psiuReactionThermo_H
 #define psiuReactionThermo_H
 
-#include "psiReactionThermo.H"
+#include "psiThermo.H"
+#include "basicCombustionMixture.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -44,12 +45,12 @@ namespace Foam
 {
 
 /*---------------------------------------------------------------------------*\
-                           Class psiuReactionThermo Declaration
+                       Class psiuReactionThermo Declaration
 \*---------------------------------------------------------------------------*/
 
 class psiuReactionThermo
 :
-    public psiReactionThermo
+    public psiThermo
 {
 
 protected:
@@ -106,6 +107,12 @@ public:
         //- Update properties
         virtual void correct() = 0;
 
+        //- Return the composition of the combustion mixture
+        virtual basicCombustionMixture& composition() = 0;
+
+        //- Return the composition of the combustion mixture
+        virtual const basicCombustionMixture& composition() const = 0;
+
 
         // Access to thermodynamic state variables.