twist and boundary conditions for free propagator

Grid/qcd/action/fermion/DomainWallFermion.h

@@ -43,7 +43,7 @@ namespace Grid {
      INHERIT_IMPL_TYPES(Impl);
     public:
 
-      void FreePropagator(const FermionField &in,FermionField &out,RealD mass, std::vector<double> twist, bool fiveD) {
+      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);
 
@@ -55,15 +55,19 @@ namespace Grid {
 	FermionField in_buf(in._grid); in_buf = zero;
 	Complex 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);
-	  ph = ph + twist[nu]*coor*((1./(in._grid->_fdimensions[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((Real)(2.0*M_PI)*ci*ph*(-1.0))*in;
+	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;
@@ -76,25 +80,28 @@ namespace Grid {
           this->MomentumSpacePropagatorHt(prop_k,in_k,mass,twist);
 	  theFFT.FFT_all_dim(out,prop_k,FFT::backward);
         }
-
 	//phase for boundary condition
-	out = out * exp((Real)(2.0*M_PI)*ci*ph);
+	out = out * exp(ci*ph);
       };
 
-      virtual void FreePropagator(const FermionField &in,FermionField &out,RealD mass,std::vector<double> twist) {
+      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,twist,fiveD);
+	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
-        FreePropagator(in,out,mass,twist,fiveD);
+	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: periodic boundarys in all directions
+	std::vector<double> twist(Nd,0.0); //default: twist angle 0
-        FreePropagator(in,out,mass,twist,fiveD);
+	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) {};

Grid/qcd/action/fermion/FermionOperator.h

@@ -96,7 +96,7 @@ namespace Grid {
 
       virtual void  MomentumSpacePropagator(FermionField &out,const FermionField &in,RealD _m,std::vector<double> twist) { assert(0);};
 
-      virtual void  FreePropagator(const FermionField &in,FermionField &out,RealD mass,std::vector<double> twist) {
+      virtual void  FreePropagator(const FermionField &in,FermionField &out,RealD mass,std::vector<Complex> boundary,std::vector<double> twist) {
 	FFT theFFT((GridCartesian *) in._grid);
 
 	FermionField in_k(in._grid);
@@ -108,24 +108,31 @@ namespace Grid {
 	FermionField in_buf(in._grid); in_buf = zero;
 	Complex ci(0.0,1.0);
 	assert(twist.size() == Nd);//check that twist is Nd
+	assert(boundary.size() == Nd);//check that boundary conditions is Nd
 	for(unsigned int nu = 0; nu < Nd; nu++)
 	{
           LatticeCoordinate(coor, nu);
-	  ph = ph + twist[nu]*coor*((1./(in._grid->_fdimensions[nu])));
+	  double boundary_phase = ::acos(real(boundary[nu]));
+	  ph = ph + boundary_phase*coor*((1./(in._grid->_fdimensions[nu])));
+	  //momenta for propagator shifted by twist+boundary
+	  twist[nu] = twist[nu] + boundary_phase/((2.0*M_PI));
 	}
-	in_buf = exp((Real)(2.0*M_PI)*ci*ph*(-1.0))*in;
+	in_buf = exp(ci*ph*(-1.0))*in;
 
 	theFFT.FFT_all_dim(in_k,in_buf,FFT::forward);
         this->MomentumSpacePropagator(prop_k,in_k,mass,twist);
 	theFFT.FFT_all_dim(out,prop_k,FFT::backward);
 
 	//phase for boundary condition
-	out = out * exp((Real)(2.0*M_PI)*ci*ph);
+	out = out * exp(ci*ph);
 
       };
+
       virtual void FreePropagator(const FermionField &in,FermionField &out,RealD mass) {
+		std::vector<Complex> boundary;
+		for(int i=0;i<Nd;i++) boundary.push_back(1);//default: periodic boundary conditions
 		std::vector<double> twist(Nd,0.0); //default: periodic boundarys in all directions
-	        FreePropagator(in,out,mass,twist);
+	        FreePropagator(in,out,mass,boundary,twist);
       };
 
       ///////////////////////////////////////////////

Hadrons/Modules/MFermion/EMLepton.hpp

@@ -72,6 +72,7 @@ public:
 				    std::string,  action,
 				    std::string, emField,
 				    double, mass,
+                                    std::string , boundary,
 				    std::string,  twist,
                                     unsigned int, deltat);
 };
@@ -163,8 +164,7 @@ void TEMLepton<FImpl>::execute(void)
     envGetTmp(FermionField, sol);
     envGetTmp(FermionField, tmp);
     LOG(Message) << "Calculating a lepton Propagator with sequential Aslash insertion with lepton mass " 
-                 << mass << " and twist ("
+                 << mass << " using the action '" << par().action
-                 << par().twist << ") using the action '" << par().action
                  << "' for fixed source-sink separation of " << par().deltat << std::endl;
 
     envGetTmp(Lattice<iScalar<vInteger>>, tlat);
@@ -176,6 +176,11 @@ void TEMLepton<FImpl>::execute(void)
     {
 	HADRONS_ERROR(Size, "number of twist angles does not match number of dimensions");
     }
+    std::vector<Complex> boundary = strToVec<Complex>(par().boundary);
+    if(boundary.size() != Nd)
+    {
+	HADRONS_ERROR(Size, "number of boundary conditions does not match number of dimensions");
+    }
 
     auto &stoch_photon = envGet(EmField,  par().emField);
     unsigned int nt = env().getDim(Tp);
@@ -212,7 +217,7 @@ void TEMLepton<FImpl>::execute(void)
 	    mat.ImportPhysicalFermionSource(tmp, source);
 	}
         sol = zero;
-	mat.FreePropagator(source,sol,mass,twist);
+	mat.FreePropagator(source,sol,mass,boundary,twist);
 	if (Ls_ == 1)
 	{
             FermToProp<FImpl>(freetmp, sol, s, 0);
@@ -229,11 +234,7 @@ void TEMLepton<FImpl>::execute(void)
 
 	//shift free propagator to different source positions
 	proptmp = Cshift(freetmp,Tp, -tl);
-        //take anti-periodic boundary conditions into account, if used
+	proptmp = where( tlat < tl, boundary[Tp]*proptmp, proptmp);
-        if(twist[Tp]==0.5)
-        {
-	      proptmp = where( tlat < tl, (-1.0)*proptmp, proptmp);
-        }	
 
         // free propagator for fixed source-sink separation 
 	lep = where(tlat == (tl-par().deltat+nt)%nt, proptmp, lep);
@@ -264,7 +265,7 @@ void TEMLepton<FImpl>::execute(void)
 		mat.ImportPhysicalFermionSource(tmp, source);
 	    }
             sol = zero;
-	    mat.FreePropagator(source,sol,mass,twist);
+	    mat.FreePropagator(source,sol,mass,boundary,twist);
 	    if (Ls_ == 1)
 	    {
         	FermToProp<FImpl>(proptmp, sol, s, 0);

Hadrons/Modules/MFermion/FreeProp.hpp

@@ -49,6 +49,7 @@ public:
                                     std::string, source,
 				    std::string,  action,
 				    double, mass,
+                                    std::string , boundary,
 				    std::string,  twist);
 };
 
@@ -172,7 +173,12 @@ void TFreeProp<FImpl>::execute(void)
 	{
 	    HADRONS_ERROR(Size, "number of twist angles does not match number of dimensions");
 	}
-	mat.FreePropagator(source,sol,mass,twist);
+	std::vector<Complex> boundary = strToVec<Complex>(par().boundary);
+	if(boundary.size() != Nd)
+	{
+	    HADRONS_ERROR(Size, "number of boundary conditions does not match number of dimensions");
+	}
+	mat.FreePropagator(source,sol,mass,boundary,twist);
         FermToProp<FImpl>(prop, sol, s, c);
         // create 4D propagators from 5D one if necessary
         if (Ls_ > 1)