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Added cloverleaf energy density calculation to WilsonFlow

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This commit is contained in:
Christopher Kelly 2021-12-27 10:33:33 -05:00
parent 551b93ba8e
commit c4ac528126
1 changed files with 59 additions and 1 deletions
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60
Grid/qcd/smearing/WilsonFlow.h
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@ -7,6 +7,7 @@ Source file: ./lib/qcd/modules/plaquette.h
Copyright (C) 2017
Author: Guido Cossu <guido.cossu@ed.ac.uk>
Author: Christopher Kelly <ckelly@bnl.gov>
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
@ -80,12 +81,22 @@ public:
//Compute t^2 <E(t)> for time taus, set by smear_adaptive, from the plaquette
RealD energyDensityPlaquette(const GaugeField& U) const;
//Evolve the gauge field by Nstep steps of epsilon and return the energy density computed every interval steps
//The smeared field is output as V
std::vector<RealD> flowMeasureEnergyDensityPlaquette(GaugeField &V, const GaugeField& U) const;
std::vector<RealD> flowMeasureEnergyDensityPlaquette(const GaugeField& U) const;
//Compute t^2 <E(t)> for time from the 1x1 cloverleaf form
//t is the Wilson flow time
RealD energyDensityCloverleaf(RealD t, const GaugeField& U) const;
//Evolve the gauge field by Nstep steps of epsilon and return the Cloverleaf energy density computed every interval steps
//The smeared field is output as V
std::vector<RealD> flowMeasureEnergyDensityCloverleaf(GaugeField &V, const GaugeField& U) const;
std::vector<RealD> flowMeasureEnergyDensityCloverleaf(const GaugeField& U) const;
};
@ -185,6 +196,53 @@ std::vector<RealD> WilsonFlow<Gimpl>::flowMeasureEnergyDensityPlaquette(const Ga
return flowMeasureEnergyDensityPlaquette(V,U);
}
//Compute t^2 <E(t)> for time from the 1x1 cloverleaf form
template <class Gimpl>
RealD WilsonFlow<Gimpl>::energyDensityCloverleaf(RealD t, const GaugeField& U) const{
typedef typename Gimpl::GaugeLinkField GaugeMat;
typedef typename Gimpl::GaugeField GaugeLorentz;
assert(Nd == 4);
//E = 1/2 tr( F_munu F_munu )
//However as F_numu = -F_munu, only need to sum the trace of the squares of the following 6 field strengths:
//F_01 F_02 F_03 F_12 F_13 F_23
GaugeMat F(U.Grid());
LatticeComplexD R(U.Grid());
R = Zero();
for(int mu=0;mu<3;mu++){
for(int nu=mu+1;nu<4;nu++){
WilsonLoops<Gimpl>::FieldStrength(F, U, mu, nu);
R = R + trace(F*F);
}
}
ComplexD out = sum(R);
out = t*t*out / RealD(U.Grid()->gSites());
return -real(out); //minus sign necessary for +ve energy
}
template <class Gimpl>
std::vector<RealD> WilsonFlow<Gimpl>::flowMeasureEnergyDensityCloverleaf(GaugeField &V, const GaugeField& U) const{
std::vector<RealD> out;
V = U;
for (unsigned int step = 0; step < Nstep; step++) { //bn tau = epsilon*(step+1) so tau after performing step=0 is epsilon
std::cout << GridLogMessage << "[WilsonFlow] Evolving step " << step << std::endl;
evolve_step(V);
if( step % measure_interval == 0){
std::cout << GridLogMessage << "[WilsonFlow] Computing Cloverleaf energy density for step " << step << std::endl;
out.push_back( energyDensityCloverleaf(tau(step),V) );
}
}
return out;
}
template <class Gimpl>
std::vector<RealD> WilsonFlow<Gimpl>::flowMeasureEnergyDensityCloverleaf(const GaugeField& U) const{
GaugeField V(U);
return flowMeasureEnergyDensityCloverleaf(V,U);
}
//#define WF_TIMING
template <class Gimpl>