diff --git a/Code/Mantid/Framework/CurveFitting/inc/MantidCurveFitting/DiffRotDiscreteCircle.h b/Code/Mantid/Framework/CurveFitting/inc/MantidCurveFitting/DiffRotDiscreteCircle.h
index 0e711510bc02..9ae2af98d07c 100644
--- a/Code/Mantid/Framework/CurveFitting/inc/MantidCurveFitting/DiffRotDiscreteCircle.h
+++ b/Code/Mantid/Framework/CurveFitting/inc/MantidCurveFitting/DiffRotDiscreteCircle.h
@@ -53,6 +53,9 @@ class DLLExport ElasticDiffRotDiscreteCircle : public DeltaFunction
   /// overwrite IFunction base class methods
   virtual std::string name()const{ return "ElasticDiffRotDiscreteCircle"; }
 
+  /// overwrite IFunction base class method, which declare function parameters
+  virtual void init();
+
   /// A rescaling of the peak intensity
   double HeightPrefactor() const;
 
@@ -74,13 +77,15 @@ class DLLExport InelasticDiffRotDiscreteCircle : public API::ParamFunction, publ
 
   virtual std::string name() const { return "InelasticDiffRotDiscreteCircle"; }
 
+  virtual void init();
+
 protected:
 
   virtual void function1D( double * out, const double* xValues, const size_t nData ) const;
 
 private:
 
-  const double m_t2e; // converstion from picosec to mili-eV, or from nanosec to micro-eV
+  const double m_h; // Plank constant, in meV*THz (or ueV*PHz)
 };
 
 
@@ -93,9 +98,6 @@ class DLLExport DiffRotDiscreteCircle : public API::ImmutableCompositeFunction
 {
 public:
 
-  /// Constructor
-  DiffRotDiscreteCircle();
-
   /// Destructor
   ~DiffRotDiscreteCircle() {};
 
@@ -105,6 +107,8 @@ class DLLExport DiffRotDiscreteCircle : public API::ImmutableCompositeFunction
 
   virtual int version() const { return 1; }
 
+  virtual void init();
+
   /// Propagate an attribute to member functions
   virtual void trickleDownAttribute( const std::string &name );
 
diff --git a/Code/Mantid/Framework/CurveFitting/src/DiffRotDiscreteCircle.cpp b/Code/Mantid/Framework/CurveFitting/src/DiffRotDiscreteCircle.cpp
index 2de63a6fc38b..c7d323e8a900 100644
--- a/Code/Mantid/Framework/CurveFitting/src/DiffRotDiscreteCircle.cpp
+++ b/Code/Mantid/Framework/CurveFitting/src/DiffRotDiscreteCircle.cpp
@@ -17,7 +17,7 @@ The Decay fitting parameter <math>\tau</math> is the inverse of the transition r
 
 <center><math> \tau_l^{-1} = 4 \tau^{-1} sin^2(\frac{\pi l}{N}) </math></center>
 
-If the unit of <math>\omega</math> is energy, and the energy unit is <math>\mu</math>eV, then <math>\tau</math> is expressed in nano-seconds. If E-unit is meV then <math>\tau</math> is expressed in pico-seconds. The conversion equation used between the jump transition rate <math>k</math>, expressed in energy units, and <math>\tau</math> is: <math>k\cdot \tau=4.136\, meV\cdot ps=4.136\, \mu eV\cdot ns</math>
+The transition rate, expressed in units of energy is <math>h\tau^{-1}</math>, with h = 4.135665616 meV THz.
 
 == Example: Methyl Rotations ==
 Methyl Rotations can be modelled setting N=3. In this case, the inelastic part reduces to a single Lorentzian:
@@ -26,10 +26,10 @@ Methyl Rotations can be modelled setting N=3. In this case, the inelastic part r
 
 If, alternatively, one models these dynamics using the [[Lorentzian]] function provided in Mantid:
 
-<center><math> S(Q,E) = A \delta (\omega) + \frac{B}{\pi} \left( \frac{\frac{\Gamma}{2}}{(\frac{\Gamma}{2})^2 + \omega^2}\right) </math></center>
-Then the following equalities hold:
-<center><math>B = 2\,A_1</math></center>
-<center><math>\Gamma = 6\cdot 4.126/\tau</math></center>
+<center><math> S(Q,E) = A \delta (\omega) + \frac{B}{\pi} \left( \frac{\frac{\Gamma}{2}}{(\frac{\Gamma}{2})^2 + (\hbar\omega)^2}\right) </math></center>
+Then:
+<center><math>B = \frac{1}{\pi}h A_1</math></center>
+<center><math>\Gamma = \frac{3}{\pi} h\tau^{-1} = 3.949269754 meV\cdot THz \cdot \tau^{-1}</math></center>
 
 == Properties ==
 
@@ -55,7 +55,6 @@ Then the following equalities hold:
 |inverse of the transition rate (ps if energy in meV; ns if energy in <math>\mu</math>eV)
 |}
 
-
 [[Category:Fit_functions]]
 *WIKI*/
 
@@ -81,17 +80,18 @@ DECLARE_FUNCTION(DiffRotDiscreteCircle);
 ElasticDiffRotDiscreteCircle::ElasticDiffRotDiscreteCircle(){
   //declareParameter("Height", 1.0); //parameter "Height" already declared in constructor of base class DeltaFunction
   declareParameter( "Radius", 1.0, "Circle radius [Angstroms] " );
+  declareAttribute( "Q", API::IFunction::Attribute(0.5) );
+  declareAttribute( "N", API::IFunction::Attribute(3) );
+}
 
+void ElasticDiffRotDiscreteCircle::init()
+{
   // Ensure positive values for Height and Radius
   BoundaryConstraint* HeightConstraint = new BoundaryConstraint( this, "Height", std::numeric_limits<double>::epsilon(), true );
   addConstraint( HeightConstraint );
 
   BoundaryConstraint* RadiusConstraint = new BoundaryConstraint( this, "Radius", std::numeric_limits<double>::epsilon(), true );
   addConstraint( RadiusConstraint );
-
-  declareAttribute( "Q", API::IFunction::Attribute(0.5) );
-  declareAttribute( "N", API::IFunction::Attribute(3) );
-
 }
 
 double ElasticDiffRotDiscreteCircle::HeightPrefactor() const{
@@ -108,7 +108,7 @@ double ElasticDiffRotDiscreteCircle::HeightPrefactor() const{
   return aN / N;
 }
 
-InelasticDiffRotDiscreteCircle::InelasticDiffRotDiscreteCircle() : m_t2e(4.136)
+InelasticDiffRotDiscreteCircle::InelasticDiffRotDiscreteCircle() : m_h(4.135665616)
 {
   declareParameter( "Intensity",1.0, "scaling factor [arbitrary units]" );
   declareParameter( "Radius", 1.0, "Circle radius [Angstroms]" );
@@ -116,7 +116,10 @@ InelasticDiffRotDiscreteCircle::InelasticDiffRotDiscreteCircle() : m_t2e(4.136)
 
   declareAttribute( "Q", API::IFunction::Attribute( 0.5 ) );
   declareAttribute( "N", API::IFunction::Attribute( 3 ) );
+}
 
+void InelasticDiffRotDiscreteCircle::init()
+{
   // Ensure positive values for Intensity, Radius, and decay
   BoundaryConstraint* IntensityConstraint = new BoundaryConstraint( this, "Intensity", std::numeric_limits< double >::epsilon(), true );
   addConstraint(IntensityConstraint);
@@ -126,15 +129,13 @@ InelasticDiffRotDiscreteCircle::InelasticDiffRotDiscreteCircle() : m_t2e(4.136)
 
   BoundaryConstraint* DecayConstraint = new BoundaryConstraint( this, "Decay", std::numeric_limits< double >::epsilon(), true );
   addConstraint( DecayConstraint );
-
 }
 
-
 void InelasticDiffRotDiscreteCircle::function1D( double *out, const double* xValues, const size_t nData ) const
 {
   const double I = getParameter( "Intensity" );
   const double R = getParameter( "Radius" );
-  const double rate = m_t2e / getParameter( "Decay" ); // micro-eV or mili-eV
+  const double rate = m_h / getParameter( "Decay" ); // micro-eV or mili-eV
   const double Q = getAttribute( "Q" ).asDouble();
   const int N = getAttribute( "N" ).asInt();
 
@@ -206,26 +207,27 @@ void DiffRotDiscreteCircle::setAttribute( const std::string& name, const Attribu
   trickleDownAttribute( name );
 }
 
-DiffRotDiscreteCircle::DiffRotDiscreteCircle()
+//DiffRotDiscreteCircle::DiffRotDiscreteCircle()
+void DiffRotDiscreteCircle::init()
 {
   m_elastic = boost::dynamic_pointer_cast<ElasticDiffRotDiscreteCircle>( API::FunctionFactory::Instance().createFunction( "ElasticDiffRotDiscreteCircle" ) );
   addFunction( m_elastic );
   m_inelastic = boost::dynamic_pointer_cast<InelasticDiffRotDiscreteCircle>( API::FunctionFactory::Instance().createFunction( "InelasticDiffRotDiscreteCircle" ) );
   addFunction( m_inelastic );
 
-  this->setAttributeValue( "NumDeriv", true );
+  setAttributeValue( "NumDeriv", true );
 
-  this->declareAttribute( "Q", API::IFunction::Attribute( 0.5 ) );
-  this->declareAttribute( "N", API::IFunction::Attribute( 3 ) );
+  declareAttribute( "Q", API::IFunction::Attribute( 0.5 ) );
+  declareAttribute( "N", API::IFunction::Attribute( 3 ) );
 
   //Set the aliases
-  this->setAlias( "f1.Intensity", "Intensity" );
-  this->setAlias( "f1.Radius", "Radius" );
-  this->setAlias( "f1.Decay", "Decay" );
+  setAlias( "f1.Intensity", "Intensity" );
+  setAlias( "f1.Radius", "Radius" );
+  setAlias( "f1.Decay", "Decay" );
 
   //Set the ties between Elastic and Inelastic parameters
-  this->addDefaultTies( "f0.Height=f1.Intensity,f0.Radius=f1.Radius" );
-  this->applyTies();
+  addDefaultTies( "f0.Height=f1.Intensity,f0.Radius=f1.Radius" );
+  applyTies();
 
 }
 
diff --git a/Code/Mantid/Framework/CurveFitting/test/DiffRotDiscreteCircleTest.h b/Code/Mantid/Framework/CurveFitting/test/DiffRotDiscreteCircleTest.h
index b39bdfefccd3..66414510910a 100644
--- a/Code/Mantid/Framework/CurveFitting/test/DiffRotDiscreteCircleTest.h
+++ b/Code/Mantid/Framework/CurveFitting/test/DiffRotDiscreteCircleTest.h
@@ -189,6 +189,7 @@ class DiffRotDiscreteCircleTest :  public CxxTest::TestSuite
     const double Q = 0.7;
     const int N = 4;
     Mantid::CurveFitting::DiffRotDiscreteCircle func;
+    func.init();
     func.setParameter( "f1.Intensity", I );
     func.setParameter( "f1.Radius" , R );
     func.setParameter( "f1.Decay", tao );
@@ -221,6 +222,7 @@ class DiffRotDiscreteCircleTest :  public CxxTest::TestSuite
 
     // This should set parameters of the inelastic part
     Mantid::CurveFitting::DiffRotDiscreteCircle func;
+    func.init();
     func.setParameter( "Intensity", I );
     func.setParameter( "Radius", R );
     func.setParameter( "Decay", tao );
@@ -338,7 +340,8 @@ class DiffRotDiscreteCircleTest :  public CxxTest::TestSuite
    */
   Mantid::DataObjects::Workspace2D_sptr generateN3Workspace( const double & I, const double & R, const double & tao, const double & Q )
   {
-    const double rate = 4.136 / tao; // conversion from picosec to mili-eV, or from nanosec to micro-eV
+    const double h = 4.135665616; // plank constant in meV*THz (or ueV*PHz)
+    const double rate = h / tao; // conversion from picosec to mili-eV, or from nanosec to micro-eV
 
     // calculate prefix A1. Better be verbose for clarity
     const double x = Q * R * sqrt( 3.0 );