rpg/fts/brownian/LMBdStep.h

#ifndef RPG_LM_BD_STEP_H
#define RPG_LM_BD_STEP_H
 
/*
* PSCF - Polymer Self-Consistent Field
*
* Copyright 2015 - 2025, The Regents of the University of Minnesota
* Distributed under the terms of the GNU General Public License.
*/
 
 
#include "BdStep.h"                       // base class
#include <prdc/cuda/RField.h>             // member
#include <util/containers/DArray.h>       // member
 
namespace Pscf {
namespace Rpg {
 
   using namespace Util;
   using namespace Pscf::Prdc;
   using namespace Pscf::Prdc::Cuda;

   template <int D>
   class LMBdStep : public BdStep<D>
   {
 
   public:

      LMBdStep(BdSimulator<D>& simulator);

      virtual ~LMBdStep();

      virtual void readParameters(std::istream &in);

      virtual void setup();

      virtual bool step();
 
   protected:
 
      using BdStep<D>::system;
      using BdStep<D>::simulator;
      using BdStep<D>::cudaRandom;
      using ParamComposite::read;
 
   private:
 
      // Private data members
 
      // New field values
      DArray< RField<D> > w_;
 
      // Random displacements (A)
      DArray< RField<D> > etaA_;
 
      // Random displacements (B)
      DArray< RField<D> > etaB_;
 
      // Change in one field component
      RField<D> dwc_;
 
      // Pointer to new random displacements
      DArray< RField<D> >* etaNewPtr_;
 
      // Pointer to old random displacements
      DArray< RField<D> >* etaOldPtr_;
      
      // Normal-distributed random fields
      RField<D> gaussianField_;
 
      // Prefactor of -dc_ in deterministic drift term
      double mobility_;
 
      // Private member functions
 
      RField<D>& etaNew(int i) 
      {   return (*etaNewPtr_)[i]; }
 
      RField<D>& etaOld(int i) 
      {   return (*etaOldPtr_)[i]; }

      void generateEtaNew();

      void exchangeOldNew();
 
   };
 
   // Explicit instantiation declarations
   extern template class LMBdStep<1>;
   extern template class LMBdStep<2>;
   extern template class LMBdStep<3>;
 
}
}
#endif