DomainWallFermion.h

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/*************************************************************************************
 
    Grid physics library, www.github.com/paboyle/Grid 
 
    Source file: ./lib/qcd/action/fermion/DomainWallFermion.h
 
    Copyright (C) 2015
 
Author: Peter Boyle <pabobyle@ph.ed.ac.uk>
Author: Peter Boyle <paboyle@ph.ed.ac.uk>
Author: Vera Guelpers <V.M.Guelpers@soton.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 */
#ifndef  GRID_QCD_DOMAIN_WALL_FERMION_H
#define  GRID_QCD_DOMAIN_WALL_FERMION_H
 
#include <Grid/qcd/action/fermion/FermionCore.h>
 
NAMESPACE_BEGIN(Grid);
 
template<class Impl>
class DomainWallFermion : public CayleyFermion5D<Impl>
{
public:
  INHERIT_IMPL_TYPES(Impl);
public:
 
  void FreePropagator(const FermionField &in,FermionField &out,RealD mass,std::vector<Complex> boundary, std::vector<double> twist, bool fiveD) {
    FermionField in_k(in.Grid());
    FermionField prop_k(in.Grid());
 
    FFT theFFT((GridCartesian *) in.Grid());
 
    //phase for boundary condition
    ComplexField coor(in.Grid());
    ComplexField ph(in.Grid());  ph = Zero();
    FermionField in_buf(in.Grid()); in_buf = Zero();
    typedef typename Simd::scalar_type Scalar;
    Scalar ci(0.0,1.0);
    assert(twist.size() == Nd);//check that twist is Nd
    assert(boundary.size() == Nd);//check that boundary conditions is Nd
    int shift = 0;
    if(fiveD) shift = 1;
    for(unsigned int nu = 0; nu < Nd; nu++)
    {
      // Shift coordinate lattice index by 1 to account for 5th dimension.
          LatticeCoordinate(coor, nu + shift);
      double boundary_phase = ::acos(real(boundary[nu]));
      ph = ph + boundary_phase*coor*((1./(in.Grid()->_fdimensions[nu+shift])));
      //momenta for propagator shifted by twist+boundary
      twist[nu] = twist[nu] + boundary_phase/((2.0*M_PI));
    }
    in_buf = exp(ci*ph*(-1.0))*in;
 
    if(fiveD){//FFT only on temporal and spatial dimensions
          std::vector<int> mask(Nd+1,1); mask[0] = 0;
      theFFT.FFT_dim_mask(in_k,in_buf,mask,FFT::forward);
          this->MomentumSpacePropagatorHt_5d(prop_k,in_k,mass,twist);
          theFFT.FFT_dim_mask(out,prop_k,mask,FFT::backward);
        }
    else{
      theFFT.FFT_all_dim(in_k,in,FFT::forward);
          this->MomentumSpacePropagatorHt(prop_k,in_k,mass,twist);
      theFFT.FFT_all_dim(out,prop_k,FFT::backward);
        }
    //phase for boundary condition
    out = out * exp(ci*ph);
      };
 
      virtual void FreePropagator(const FermionField &in,FermionField &out,RealD mass,std::vector<Complex> boundary,std::vector<double> twist) {
        bool fiveD = true; //5d propagator by default
    FreePropagator(in,out,mass,boundary,twist,fiveD);
      };
 
      virtual void FreePropagator(const FermionField &in,FermionField &out,RealD mass, bool fiveD) {
    std::vector<double> twist(Nd,0.0); //default: periodic boundarys in all directions
    std::vector<Complex> boundary;
    for(int i=0;i<Nd;i++) boundary.push_back(1);//default: periodic boundary conditions
    FreePropagator(in,out,mass,boundary,twist,fiveD);
      };
 
      virtual void FreePropagator(const FermionField &in,FermionField &out,RealD mass) {
        bool fiveD = true; //5d propagator by default
    std::vector<double> twist(Nd,0.0); //default: twist angle 0
    std::vector<Complex> boundary;
    for(int i=0;i<Nd;i++) boundary.push_back(1); //default: periodic boundary conditions
    FreePropagator(in,out,mass,boundary,twist,fiveD);
      };
 
  virtual void   Instantiatable(void) {};
  // Constructors
  DomainWallFermion(GaugeField &_Umu,
            GridCartesian         &FiveDimGrid,
            GridRedBlackCartesian &FiveDimRedBlackGrid,
            GridCartesian         &FourDimGrid,
            GridRedBlackCartesian &FourDimRedBlackGrid,
            RealD _mass,RealD _M5,const ImplParams &p= ImplParams()) : 
 
 
    CayleyFermion5D<Impl>(_Umu,
              FiveDimGrid,
              FiveDimRedBlackGrid,
              FourDimGrid,
              FourDimRedBlackGrid,_mass,_M5,p)
 
  {
    RealD eps = 1.0;
 
    Approx::zolotarev_data *zdata = Approx::higham(eps,this->Ls);// eps is ignored for higham
    assert(zdata->n==this->Ls);
    
    //    std::cout<<GridLogMessage << "DomainWallFermion with Ls="<<this->Ls<<std::endl;
    // Call base setter
    this->SetCoefficientsTanh(zdata,1.0,0.0);
 
    Approx::zolotarev_free(zdata);
  }
 
};
 
NAMESPACE_END(Grid);
 
#endif