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Grid/lib/qcd/action/pseudofermion/TwoFlavour.h

150 lines
4.9 KiB
C++

/*************************************************************************************
Grid physics library, www.github.com/paboyle/Grid
Source file: ./lib/qcd/action/pseudofermion/TwoFlavour.h
Copyright (C) 2015
Author: Peter Boyle <pabobyle@ph.ed.ac.uk>
Author: Peter Boyle <paboyle@ph.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 */
#ifndef QCD_PSEUDOFERMION_TWO_FLAVOUR_H
#define QCD_PSEUDOFERMION_TWO_FLAVOUR_H
namespace Grid{
namespace QCD{
////////////////////////////////////////////////////////////////////////
// Two flavour pseudofermion action for any dop
////////////////////////////////////////////////////////////////////////
template<class Impl>
class TwoFlavourPseudoFermionAction : public Action<typename Impl::GaugeField> {
public:
INHERIT_IMPL_TYPES(Impl);
private:
FermionOperator<Impl> & FermOp;// the basic operator
OperatorFunction<FermionField> &DerivativeSolver;
OperatorFunction<FermionField> &ActionSolver;
FermionField Phi; // the pseudo fermion field for this trajectory
public:
/////////////////////////////////////////////////
// Pass in required objects.
/////////////////////////////////////////////////
TwoFlavourPseudoFermionAction(FermionOperator<Impl> &Op,
OperatorFunction<FermionField> & DS,
OperatorFunction<FermionField> & AS
) : FermOp(Op), DerivativeSolver(DS), ActionSolver(AS), Phi(Op.FermionGrid()) {
};
//////////////////////////////////////////////////////////////////////////////////////
// Push the gauge field in to the dops. Assume any BC's and smearing already applied
//////////////////////////////////////////////////////////////////////////////////////
virtual void refresh(const GaugeField &U, GridParallelRNG& pRNG) {
// P(phi) = e^{- phi^dag (MdagM)^-1 phi}
// Phi = Mdag eta
// P(eta) = e^{- eta^dag eta}
//
// e^{x^2/2 sig^2} => sig^2 = 0.5.
//
// So eta should be of width sig = 1/sqrt(2).
// and must multiply by 0.707....
//
// Chroma has this scale factor: two_flavor_monomial_w.h
// IroIro: does not use this scale. It is absorbed by a change of vars
// in the Phi integral, and thus is only an irrelevant prefactor for the partition function.
//
RealD scale = std::sqrt(0.5);
FermionField eta(FermOp.FermionGrid());
gaussian(pRNG,eta);
FermOp.ImportGauge(U);
FermOp.Mdag(eta,Phi);
Phi=Phi*scale;
};
//////////////////////////////////////////////////////
// S = phi^dag (Mdag M)^-1 phi
//////////////////////////////////////////////////////
virtual RealD S(const GaugeField &U) {
FermOp.ImportGauge(U);
FermionField X(FermOp.FermionGrid());
FermionField Y(FermOp.FermionGrid());
MdagMLinearOperator<FermionOperator<Impl> ,FermionField> MdagMOp(FermOp);
X=zero;
ActionSolver(MdagMOp,Phi,X);
MdagMOp.Op(X,Y);
RealD action = norm2(Y);
std::cout << GridLogMessage << "Pseudofermion action "<<action<<std::endl;
return action;
};
//////////////////////////////////////////////////////
// dS/du = - phi^dag (Mdag M)^-1 [ Mdag dM + dMdag M ] (Mdag M)^-1 phi
// = - phi^dag M^-1 dM (MdagM)^-1 phi - phi^dag (MdagM)^-1 dMdag dM (Mdag)^-1 phi
//
// = - Ydag dM X - Xdag dMdag Y
//
//////////////////////////////////////////////////////
virtual void deriv(const GaugeField &U,GaugeField & dSdU) {
FermOp.ImportGauge(U);
FermionField X(FermOp.FermionGrid());
FermionField Y(FermOp.FermionGrid());
GaugeField tmp(FermOp.GaugeGrid());
MdagMLinearOperator<FermionOperator<Impl> ,FermionField> MdagMOp(FermOp);
X=zero;
DerivativeSolver(MdagMOp,Phi,X);
MdagMOp.Op(X,Y);
// Our conventions really make this UdSdU; We do not differentiate wrt Udag here.
// So must take dSdU - adj(dSdU) and left multiply by mom to get dS/dt.
FermOp.MDeriv(tmp , Y, X,DaggerNo ); dSdU=tmp;
FermOp.MDeriv(tmp , X, Y,DaggerYes); dSdU=dSdU+tmp;
//dSdU = Ta(dSdU);
};
};
}
}
#endif