fts/brownian/LMBdStep.h

#ifndef RP_LM_BD_STEP_H
#define RP_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 <util/containers/DArray.h>    // member
 
namespace Pscf {
namespace Rp {
 
   using namespace Util;

   template <int D, class T>
   class LMBdStep : public T::BdStep
   {
   public:
 
      // Protected constructor and destructor (see below).

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

      void setup() override;

      bool step() override;
 
   protected:

      LMBdStep(typename T::BdSimulator& simulator);
 
      ~LMBdStep() = default;
 
      // Alias for base class.
      using BdStepT = typename T::BdStep;
 
      // Inherited functions (selected)
      using BdStepT::system;
      using BdStepT::simulator;
      using BdStepT::vecRandom;
 
   private:
 
      using RFieldT = typename T::RField;
 
      // Private data members
 
      // New field values
      DArray< RFieldT > w_;
 
      // Random displacements (A)
      DArray< RFieldT > etaA_;
 
      // Random displacements (B)
      DArray< RFieldT > etaB_;
 
      // Change in one field component
      RFieldT dwc_;
 
      // Pointer to new random displacements
      DArray< RFieldT >* etaNewPtr_;
 
      // Pointer to old random displacements
      DArray< RFieldT >* etaOldPtr_;
 
      // Prefactor of -dc_ in deterministic drift term
      double mobility_;
 
      // Private member functions
 
      RFieldT& etaNew(int i)
      {  return (*etaNewPtr_)[i]; }
 
      RFieldT& etaOld(int i)
      {  return (*etaOldPtr_)[i]; }

      void generateEtaNew();

      void exchangeOldNew();
 
   };
 
}
}
#endif