topological_charge.h

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/*************************************************************************************
 
Grid physics library, www.github.com/paboyle/Grid
 
Source file: ./lib/qcd/modules/topological_charge.h
 
Copyright (C) 2017
 
Author: Guido Cossu <guido.cossu@ed.ac.uk>
 
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
 
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.
 
You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
See the full license in the file "LICENSE" in the top level distribution
directory
*************************************************************************************/
               /*  END LEGAL */
 
#pragma once
 
NAMESPACE_BEGIN(Grid);
 
 
struct TopologySmearingParameters : Serializable {
  GRID_SERIALIZABLE_CLASS_MEMBERS(TopologySmearingParameters,
                  int, meas_interval,
                  float, init_step_size,
                  float, maxTau,
                  float, tolerance);
 
 TopologySmearingParameters(float ss = 0.0f, int mi = 0, float mT = 0.0f, float tol = 1e-4):
  init_step_size(ss), meas_interval(mi), maxTau(mT), tolerance(tol){}
 
  template < class ReaderClass >
  TopologySmearingParameters(Reader<ReaderClass>& Reader){
    read(Reader, "Smearing", *this);  
  }  
};
 
 
 
struct TopologyObsParameters : Serializable {
  GRID_SERIALIZABLE_CLASS_MEMBERS(TopologyObsParameters,
                  int, interval,
                  bool, do_smearing,
                  TopologySmearingParameters, Smearing);  
 
  TopologyObsParameters(int interval = 1, bool smearing = false):
    interval(interval), Smearing(smearing){}
 
  template <class ReaderClass >
  TopologyObsParameters(Reader<ReaderClass>& Reader){
    read(Reader, "TopologyMeasurement", *this);
  }
};
 
 
// this is only defined for a gauge theory
template <class Impl>
class TopologicalCharge : public HmcObservable<typename Impl::Field> {
  TopologyObsParameters Pars;
 
public:
  // here forces the Impl to be of gauge fields
  // if not the compiler will complain
  INHERIT_GIMPL_TYPES(Impl);
 
  // necessary for HmcObservable compatibility
  typedef typename Impl::Field Field;
 
  TopologicalCharge(int interval = 1, bool do_smearing = false):
    Pars(interval, do_smearing){}
    
  TopologicalCharge(TopologyObsParameters P):Pars(P){
    std::cout << GridLogDebug << "Creating TopologicalCharge " << std::endl;
  }
 
  void TrajectoryComplete(int traj,
              Field &U,
              GridSerialRNG &sRNG,
              GridParallelRNG &pRNG) {
 
    if (traj%Pars.interval == 0){
      // Smearing
      Field Usmear = U;
      int def_prec = std::cout.precision();
        
      if (Pars.do_smearing){
    // using wilson flow by default here
    WilsonFlowAdaptive<PeriodicGimplR> WF(Pars.Smearing.init_step_size, Pars.Smearing.maxTau, Pars.Smearing.tolerance, Pars.Smearing.meas_interval);
    WF.smear(Usmear, U);
    Real T0   = WF.energyDensityPlaquette(Pars.Smearing.maxTau, Usmear);
    std::cout << GridLogMessage << std::setprecision(std::numeric_limits<Real>::digits10 + 1)
          << "T0                : [ " << traj << " ] "<< T0 << std::endl;
      }
 
      Real q    = WilsonLoops<Impl>::TopologicalCharge(Usmear);
      std::cout << GridLogMessage
        << std::setprecision(std::numeric_limits<Real>::digits10 + 1)
        << "Topological Charge: [ " << traj << " ] "<< q << std::endl;
 
      std::cout.precision(def_prec);
    }
  }
 
};
 
NAMESPACE_END(Grid);