diff --git a/src/lagrangian/cfdemParticle/subModels/chemistryModel/chemistryModel/chemistryModel.H b/src/lagrangian/cfdemParticle/subModels/chemistryModel/chemistryModel/chemistryModel.H
index bea9c93c..5adb318b 100644
--- a/src/lagrangian/cfdemParticle/subModels/chemistryModel/chemistryModel/chemistryModel.H
+++ b/src/lagrangian/cfdemParticle/subModels/chemistryModel/chemistryModel/chemistryModel.H
@@ -95,11 +95,9 @@ public:
 
        virtual void execute() = 0;
        
-        virtual tmp<volScalarField> Smi (const label i) const = 0;
-
-        virtual tmp<volScalarField> Sm () const = 0;
-
+       virtual tmp<volScalarField> Smi (const label i) const {}
 
+       virtual tmp<volScalarField> Sm () const {}
 };