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87 lines
2.8 KiB
C++
87 lines
2.8 KiB
C++
/*************************************************************************************
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Grid physics library, www.github.com/paboyle/Grid
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Source file: ./lib/qcd/action/gauge/WilsonGaugeAction.h
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Copyright (C) 2015
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Author: Azusa Yamaguchi <ayamaguc@staffmail.ed.ac.uk>
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Author: Peter Boyle <paboyle@ph.ed.ac.uk>
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Author: neo <cossu@post.kek.jp>
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Author: paboyle <paboyle@ph.ed.ac.uk>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along
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with this program; if not, write to the Free Software Foundation, Inc.,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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See the full license in the file "LICENSE" in the top level distribution directory
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*************************************************************************************/
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/* END LEGAL */
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#ifndef QCD_WILSON_GAUGE_ACTION_H
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#define QCD_WILSON_GAUGE_ACTION_H
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namespace Grid{
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namespace QCD{
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////////////////////////////////////////////////////////////////////////
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// Wilson Gauge Action .. should I template the Nc etc..
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////////////////////////////////////////////////////////////////////////
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template<class Gimpl>
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class WilsonGaugeAction : public Action<typename Gimpl::GaugeField> {
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public:
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INHERIT_GIMPL_TYPES(Gimpl);
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// typedef LorentzScalar<GaugeField> GaugeLinkField;
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private:
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RealD beta;
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public:
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WilsonGaugeAction(RealD b):beta(b){};
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virtual void refresh(const GaugeField &U, GridParallelRNG& pRNG) {}; // noop as no pseudoferms
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virtual RealD S(const GaugeField &U) {
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RealD plaq = WilsonLoops<Gimpl>::avgPlaquette(U);
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RealD vol = U._grid->gSites();
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RealD action=beta*(1.0 -plaq)*(Nd*(Nd-1.0))*vol*0.5;
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return action;
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};
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virtual void deriv(const GaugeField &U,GaugeField & dSdU) {
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//not optimal implementation FIXME
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//extend Ta to include Lorentz indexes
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//RealD factor = 0.5*beta/RealD(Nc);
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RealD factor = 0.5*beta/RealD(Nc);
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GaugeLinkField Umu(U._grid);
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GaugeLinkField dSdU_mu(U._grid);
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for (int mu=0; mu < Nd; mu++){
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Umu = PeekIndex<LorentzIndex>(U,mu);
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// Staple in direction mu
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WilsonLoops<Gimpl>::Staple(dSdU_mu,U,mu);
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dSdU_mu = Ta(Umu*dSdU_mu)*factor;
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PokeIndex<LorentzIndex>(dSdU, dSdU_mu, mu);
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}
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};
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};
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}
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}
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#endif
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