lcm_exp_tdt.h

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// -*- C++ -*-
 
/*! @file
 * @brief Intgrator for exp(T dt)
 *
 * A component integrator to integrate exp(T dt) for the kinetic term (momenta)
 * (ie this is a leapQ like component)
 */
 
#ifndef LCM_EXPTDT_H
#define LCM_EXPTDT_H
 
 
#include "chromabase.h"
#include "update/molecdyn/hamiltonian/abs_hamiltonian.h"
#include "update/molecdyn/integrator/abs_integrator.h"
 
 
namespace Chroma 
{
 
  /*! @ingroup integrator */
  namespace LatColMatExpTdtIntegratorEnv 
  {
    extern const std::string name;
    bool registerAll();
  }
 
 
  /*! @ingroup integrator */
  struct  LatColMatExpTdtIntegratorParams
  {
    LatColMatExpTdtIntegratorParams();
    LatColMatExpTdtIntegratorParams(XMLReader& xml, const std::string& path);
    int  n_steps;
  };
 
  /*! @ingroup integrator */
  void read(XMLReader& xml_in, 
            const std::string& path,
            LatColMatExpTdtIntegratorParams& p);
 
  /*! @ingroup integrator */
  void write(XMLWriter& xml_out,
             const std::string& path, 
             const LatColMatExpTdtIntegratorParams& p);
 
  //! MD integrator interface for PQP leapfrog
  /*! @ingroup integrator
   *  Specialised to multi1d<LatticeColorMatrix>
   */
  class LatColMatExpTdtIntegrator 
    : public AbsComponentIntegrator<multi1d<LatticeColorMatrix>,
                                    multi1d<LatticeColorMatrix> > 
  {
  public:
 
    // Simplest Constructor
    LatColMatExpTdtIntegrator(int  n_steps_) : n_steps(n_steps_) {};
 
    // Construct from params struct and Hamiltonian
    LatColMatExpTdtIntegrator(const LatColMatExpTdtIntegratorParams& p) : 
      n_steps(p.n_steps) {}
 
    // Copy constructor
    LatColMatExpTdtIntegrator(const LatColMatExpTdtIntegrator& l) :
      n_steps(l.n_steps) {}
 
    // ! Destruction is automagic
    ~LatColMatExpTdtIntegrator(void) {};
 
 
    void operator()( AbsFieldState<multi1d<LatticeColorMatrix>,
                                   multi1d<LatticeColorMatrix> >& s, 
                     const Real& traj_length) const;
                            
 
    void refreshFields(AbsFieldState<multi1d<LatticeColorMatrix>,
                                   multi1d<LatticeColorMatrix> >& s) const
    {}
 
    void resetPredictors(void) const {}
 
  private:
    int  n_steps;
  };
 
}
 
 
#endif