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Grid/Grid/qcd/utils/GaugeGroup.h
2023-10-14 00:42:55 +03:00

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/*************************************************************************************
Grid physics library, www.github.com/paboyle/Grid
Source file: ./lib/qcd/utils/GaugeGroup.h
Copyright (C) 2015
Author: Azusa Yamaguchi <ayamaguc@staffmail.ed.ac.uk>
Author: Peter Boyle <paboyle@ph.ed.ac.uk>
Author: neo <cossu@post.kek.jp>
Author: paboyle <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_UTIL_GAUGEGROUP_H
#define QCD_UTIL_GAUGEGROUP_H
// Important detail: nvcc requires all template parameters to have names.
// This is the only reason why the second template parameter has a name.
#define ONLY_IF_SU \
typename dummy_name = group_name, \
typename named_dummy = std::enable_if_t < \
std::is_same<dummy_name, group_name>::value && \
is_su<dummy_name>::value >
#define ONLY_IF_Sp \
typename dummy_name = group_name, \
typename named_dummy = std::enable_if_t < \
std::is_same<dummy_name, group_name>::value && \
is_sp<dummy_name>::value >
NAMESPACE_BEGIN(Grid);
namespace GroupName {
class SU {};
class Sp {};
} // namespace GroupName
template <typename group_name>
struct is_su {
static const bool value = false;
};
template <>
struct is_su<GroupName::SU> {
static const bool value = true;
};
template <typename group_name>
struct is_sp {
static const bool value = false;
};
template <>
struct is_sp<GroupName::Sp> {
static const bool value = true;
};
template <typename group_name>
constexpr int compute_adjoint_dimension(int ncolour);
template <>
constexpr int compute_adjoint_dimension<GroupName::SU>(int ncolour) {
return ncolour * ncolour - 1;
}
template <>
constexpr int compute_adjoint_dimension<GroupName::Sp>(int ncolour) {
return ncolour / 2 * (ncolour + 1);
}
template <int ncolour, class group_name>
class GaugeGroup {
public:
static const int Dimension = ncolour;
static const int AdjointDimension =
compute_adjoint_dimension<group_name>(ncolour);
static const int AlgebraDimension =
compute_adjoint_dimension<group_name>(ncolour);
template <typename vtype>
using iSU2Matrix = iScalar<iScalar<iMatrix<vtype, 2> > >;
template <typename vtype>
using iGroupMatrix = iScalar<iScalar<iMatrix<vtype, ncolour> > >;
template <typename vtype>
using iAlgebraVector = iScalar<iScalar<iVector<vtype, AdjointDimension> > >;
template <typename vtype>
using iSUnAlgebraMatrix =
iScalar<iScalar<iMatrix<vtype, AdjointDimension> > >;
static int su2subgroups(void) { return su2subgroups(group_name()); }
//////////////////////////////////////////////////////////////////////////////////////////////////
// Types can be accessed as SU<2>::Matrix , SU<2>::vSUnMatrix,
// SU<2>::LatticeMatrix etc...
//////////////////////////////////////////////////////////////////////////////////////////////////
typedef iGroupMatrix<Complex> Matrix;
typedef iGroupMatrix<ComplexF> MatrixF;
typedef iGroupMatrix<ComplexD> MatrixD;
typedef iGroupMatrix<vComplex> vMatrix;
typedef iGroupMatrix<vComplexF> vMatrixF;
typedef iGroupMatrix<vComplexD> vMatrixD;
// For the projectors to the algebra
// these should be real...
// keeping complex for consistency with the SIMD vector types
typedef iAlgebraVector<Complex> AlgebraVector;
typedef iAlgebraVector<ComplexF> AlgebraVectorF;
typedef iAlgebraVector<ComplexD> AlgebraVectorD;
typedef iAlgebraVector<vComplex> vAlgebraVector;
typedef iAlgebraVector<vComplexF> vAlgebraVectorF;
typedef iAlgebraVector<vComplexD> vAlgebraVectorD;
typedef Lattice<vMatrix> LatticeMatrix;
typedef Lattice<vMatrixF> LatticeMatrixF;
typedef Lattice<vMatrixD> LatticeMatrixD;
typedef Lattice<vAlgebraVector> LatticeAlgebraVector;
typedef Lattice<vAlgebraVectorF> LatticeAlgebraVectorF;
typedef Lattice<vAlgebraVectorD> LatticeAlgebraVectorD;
typedef iSUnAlgebraMatrix<vComplex> vAlgebraMatrix;
typedef iSUnAlgebraMatrix<vComplexF> vAlgebraMatrixF;
typedef iSUnAlgebraMatrix<vComplexD> vAlgebraMatrixD;
typedef Lattice<vAlgebraMatrix> LatticeAlgebraMatrix;
typedef Lattice<vAlgebraMatrixF> LatticeAlgebraMatrixF;
typedef Lattice<vAlgebraMatrixD> LatticeAlgebraMatrixD;
typedef iSU2Matrix<Complex> SU2Matrix;
typedef iSU2Matrix<ComplexF> SU2MatrixF;
typedef iSU2Matrix<ComplexD> SU2MatrixD;
typedef iSU2Matrix<vComplex> vSU2Matrix;
typedef iSU2Matrix<vComplexF> vSU2MatrixF;
typedef iSU2Matrix<vComplexD> vSU2MatrixD;
typedef Lattice<vSU2Matrix> LatticeSU2Matrix;
typedef Lattice<vSU2MatrixF> LatticeSU2MatrixF;
typedef Lattice<vSU2MatrixD> LatticeSU2MatrixD;
// Private implementation details are specified in the following files:
// Grid/qcd/utils/SUn.impl
// Grid/qcd/utils/SUn.impl
// The public part of the interface follows below and refers to these
// private member functions.
#include <Grid/qcd/utils/SUn.impl.h>
#include <Grid/qcd/utils/Sp2n.impl.h>
public:
template <class cplx>
static void generator(int lieIndex, iGroupMatrix<cplx> &ta) {
return generator(lieIndex, ta, group_name());
}
static accelerator_inline void su2SubGroupIndex(int &i1, int &i2, int su2_index) {
return su2SubGroupIndex(i1, i2, su2_index, group_name());
}
static void testGenerators(void) { testGenerators(group_name()); }
static void printGenerators(void) {
for (int gen = 0; gen < AlgebraDimension; gen++) {
Matrix ta;
generator(gen, ta);
std::cout << GridLogMessage << "Nc = " << ncolour << " t_" << gen
<< std::endl;
std::cout << GridLogMessage << ta << std::endl;
}
}
template <typename LatticeMatrixType>
static void LieRandomize(GridParallelRNG &pRNG, LatticeMatrixType &out,
double scale = 1.0) {
GridBase *grid = out.Grid();
typedef typename LatticeMatrixType::vector_type vector_type;
typedef iSinglet<vector_type> vTComplexType;
typedef Lattice<vTComplexType> LatticeComplexType;
typedef typename GridTypeMapper<
typename LatticeMatrixType::vector_object>::scalar_object MatrixType;
LatticeComplexType ca(grid);
LatticeMatrixType lie(grid);
LatticeMatrixType la(grid);
ComplexD ci(0.0, scale);
MatrixType ta;
lie = Zero();
for (int a = 0; a < AlgebraDimension; a++) {
random(pRNG, ca);
ca = (ca + conjugate(ca)) * 0.5;
ca = ca - 0.5;
generator(a, ta);
la = ci * ca * ta;
lie = lie + la; // e^{i la ta}
}
taExp(lie, out);
}
static void GaussianFundamentalLieAlgebraMatrix(GridParallelRNG &pRNG,
LatticeMatrix &out,
Real scale = 1.0) {
GridBase *grid = out.Grid();
LatticeReal ca(grid);
LatticeMatrix la(grid);
Complex ci(0.0, scale);
Matrix ta;
out = Zero();
for (int a = 0; a < AlgebraDimension; a++) {
gaussian(pRNG, ca);
generator(a, ta);
la = toComplex(ca) * ta;
out += la;
}
out *= ci;
}
static void FundamentalLieAlgebraMatrix(const LatticeAlgebraVector &h,
LatticeMatrix &out,
Real scale = 1.0) {
conformable(h, out);
GridBase *grid = out.Grid();
LatticeMatrix la(grid);
Matrix ta;
out = Zero();
for (int a = 0; a < AlgebraDimension; a++) {
generator(a, ta);
la = peekColour(h, a) * timesI(ta) * scale;
out += la;
}
}
// Projects the algebra components a lattice matrix (of dimension ncol*ncol -1
// ) inverse operation: FundamentalLieAlgebraMatrix
static void projectOnAlgebra(LatticeAlgebraVector &h_out,
const LatticeMatrix &in, Real scale = 1.0) {
conformable(h_out, in);
h_out = Zero();
Matrix Ta;
for (int a = 0; a < AlgebraDimension; a++) {
generator(a, Ta);
pokeColour(h_out, -2.0 * (trace(timesI(Ta) * in)) * scale, a);
}
}
template <class vtype>
accelerator_inline static iScalar<vtype> ProjectOnGeneralGroup(const iScalar<vtype> &r) {
return ProjectOnGeneralGroup(r, group_name());
}
template <class vtype, int N>
accelerator_inline static iVector<vtype,N> ProjectOnGeneralGroup(const iVector<vtype,N> &r) {
return ProjectOnGeneralGroup(r, group_name());
}
template <class vtype,int N, typename std::enable_if< GridTypeMapper<vtype>::TensorLevel == 0 >::type * =nullptr>
accelerator_inline static iMatrix<vtype,N> ProjectOnGeneralGroup(const iMatrix<vtype,N> &arg) {
return ProjectOnGeneralGroup(arg, group_name());
}
template <int N,class vComplex_t> // Projects on the general groups U(N), Sp(2N)xZ2 i.e. determinant is allowed a complex phase.
static void ProjectOnGeneralGroup(Lattice<iVector<iScalar<iMatrix<vComplex_t, N> >, Nd> > &U) {
for (int mu = 0; mu < Nd; mu++) {
auto Umu = PeekIndex<LorentzIndex>(U, mu);
Umu = ProjectOnGeneralGroup(Umu);
}
}
template <int N,class vComplex_t>
static Lattice<iScalar<iScalar<iMatrix<vComplex_t, N> > > > ProjectOnGeneralGroup(const Lattice<iScalar<iScalar<iMatrix<vComplex_t, N> > > > &Umu) {
return ProjectOnGeneralGroup(Umu, group_name());
}
template <int N,class vComplex_t> // Projects on SU(N), Sp(2N), with unit determinant, by first projecting on general group and then enforcing unit determinant
static void ProjectOnSpecialGroup(Lattice<iScalar<iScalar<iMatrix<vComplex_t, N> > > > &Umu) {
Umu = ProjectOnGeneralGroup(Umu);
auto det = Determinant(Umu);
det = conjugate(det);
for (int i = 0; i < N; i++) {
auto element = PeekIndex<ColourIndex>(Umu, N - 1, i);
element = element * det;
PokeIndex<ColourIndex>(Umu, element, Nc - 1, i);
}
}
template <int N,class vComplex_t> // reunitarise, resimplectify... previously ProjectSUn
static void ProjectOnSpecialGroup(Lattice<iVector<iScalar<iMatrix<vComplex_t, N> >, Nd> > &U) {
// Reunitarise
for (int mu = 0; mu < Nd; mu++) {
auto Umu = PeekIndex<LorentzIndex>(U, mu);
ProjectOnSpecialGroup(Umu);
PokeIndex<LorentzIndex>(U, Umu, mu);
}
}
template <typename GaugeField>
static void HotConfiguration(GridParallelRNG &pRNG, GaugeField &out) {
typedef typename GaugeField::vector_type vector_type;
typedef iGroupMatrix<vector_type> vMatrixType;
typedef Lattice<vMatrixType> LatticeMatrixType;
LatticeMatrixType Umu(out.Grid());
LatticeMatrixType tmp(out.Grid());
for (int mu = 0; mu < Nd; mu++) {
// LieRandomize(pRNG, Umu, 1.0);
// PokeIndex<LorentzIndex>(out, Umu, mu);
gaussian(pRNG,Umu);
tmp = Ta(Umu);
taExp(tmp,Umu);
ProjectOnSpecialGroup(Umu);
// ProjectSUn(Umu);
PokeIndex<LorentzIndex>(out, Umu, mu);
}
}
template <typename GaugeField>
static void TepidConfiguration(GridParallelRNG &pRNG, GaugeField &out) {
typedef typename GaugeField::vector_type vector_type;
typedef iGroupMatrix<vector_type> vMatrixType;
typedef Lattice<vMatrixType> LatticeMatrixType;
LatticeMatrixType Umu(out.Grid());
for (int mu = 0; mu < Nd; mu++) {
LieRandomize(pRNG, Umu, 0.01);
PokeIndex<LorentzIndex>(out, Umu, mu);
}
}
template <typename GaugeField>
static void ColdConfiguration(GaugeField &out) {
typedef typename GaugeField::vector_type vector_type;
typedef iGroupMatrix<vector_type> vMatrixType;
typedef Lattice<vMatrixType> LatticeMatrixType;
LatticeMatrixType Umu(out.Grid());
Umu = 1.0;
for (int mu = 0; mu < Nd; mu++) {
PokeIndex<LorentzIndex>(out, Umu, mu);
}
}
template <typename GaugeField>
static void ColdConfiguration(GridParallelRNG &pRNG, GaugeField &out) {
ColdConfiguration(out);
}
template <typename LatticeMatrixType>
static void taProj(const LatticeMatrixType &in, LatticeMatrixType &out) {
taProj(in, out, group_name());
}
template <typename LatticeMatrixType>
static void taExp(const LatticeMatrixType &x, LatticeMatrixType &ex) {
typedef typename LatticeMatrixType::scalar_type ComplexType;
LatticeMatrixType xn(x.Grid());
RealD nfac = 1.0;
xn = x;
ex = xn + ComplexType(1.0); // 1+x
// Do a 12th order exponentiation
for (int i = 2; i <= 12; ++i) {
nfac = nfac / RealD(i); // 1/2, 1/2.3 ...
xn = xn * x; // x2, x3,x4....
ex = ex + xn * nfac; // x2/2!, x3/3!....
}
}
// Ta are hermitian (?)
// Anti herm is i Ta basis
static void LieAlgebraProject(LatticeAlgebraMatrix &out,const LatticeMatrix &in, int b)
{
conformable(in, out);
GridBase *grid = out.Grid();
LatticeComplex tmp(grid);
Matrix ta;
// Using Luchang's projection convention
// 2 Tr{Ta Tb} A_b= 2/2 delta ab A_b = A_a
autoView(out_v,out,AcceleratorWrite);
autoView(in_v,in,AcceleratorRead);
int N = ncolour;
int NNm1 = N * (N - 1);
int hNNm1= NNm1/2;
RealD sqrt_2 = sqrt(2.0);
Complex ci(0.0,1.0);
for(int su2Index=0;su2Index<hNNm1;su2Index++){
int i1, i2;
su2SubGroupIndex(i1, i2, su2Index);
int ax = su2Index*2;
int ay = su2Index*2+1;
accelerator_for(ss,grid->oSites(),1,{
// in is traceless ANTI-hermitian whereas Grid generators are Hermitian.
// trace( Ta x Ci in)
// Bet I need to move to real part with mult by -i
out_v[ss]()()(ax,b) = 0.5*(real(in_v[ss]()()(i2,i1)) - real(in_v[ss]()()(i1,i2)));
out_v[ss]()()(ay,b) = 0.5*(imag(in_v[ss]()()(i1,i2)) + imag(in_v[ss]()()(i2,i1)));
});
}
for(int diagIndex=0;diagIndex<N-1;diagIndex++){
int k = diagIndex + 1; // diagIndex starts from 0
int a = NNm1+diagIndex;
RealD scale = 1.0/sqrt(2.0*k*(k+1));
accelerator_for(ss,grid->oSites(),vComplex::Nsimd(),{
auto tmp = in_v[ss]()()(0,0);
for(int i=1;i<k;i++){
tmp=tmp+in_v[ss]()()(i,i);
}
tmp = tmp - in_v[ss]()()(k,k)*k;
out_v[ss]()()(a,b) =imag(tmp) * scale;
});
}
}
};
template <int ncolour>
using SU = GaugeGroup<ncolour, GroupName::SU>;
template <int ncolour>
using Sp = GaugeGroup<ncolour, GroupName::Sp>;
typedef SU<2> SU2;
typedef SU<3> SU3;
typedef SU<4> SU4;
typedef SU<5> SU5;
typedef SU<Nc> FundamentalMatrices;
typedef Sp<2> Sp2;
typedef Sp<4> Sp4;
typedef Sp<6> Sp6;
typedef Sp<8> Sp8;
template <int N,class vComplex_t>
static void ProjectSUn(Lattice<iScalar<iScalar<iMatrix<vComplex_t, N> > > > &Umu)
{
GaugeGroup<N,GroupName::SU>::ProjectOnSpecialGroup(Umu);
}
template <int N,class vComplex_t>
static void ProjectSUn(Lattice<iVector<iScalar<iMatrix<vComplex_t, N> >,Nd> > &U)
{
GaugeGroup<N,GroupName::SU>::ProjectOnSpecialGroup(U);
}
template <int N,class vComplex_t>
static void ProjectSpn(Lattice<iScalar<iScalar<iMatrix<vComplex_t, N> > > > &Umu)
{
GaugeGroup<N,GroupName::Sp>::ProjectOnSpecialGroup(Umu);
}
template <int N,class vComplex_t>
static void ProjectSpn(Lattice<iVector<iScalar<iMatrix<vComplex_t, N> >,Nd> > &U)
{
GaugeGroup<N,GroupName::Sp>::ProjectOnSpecialGroup(U);
}
// Explicit specialisation for SU(3).
static void ProjectSU3(Lattice<iScalar<iScalar<iMatrix<vComplexD, 3> > > > &Umu)
{
GridBase *grid = Umu.Grid();
const int x = 0;
const int y = 1;
const int z = 2;
// Reunitarise
Umu = ProjectOnGroup(Umu);
autoView(Umu_v, Umu, CpuWrite);
thread_for(ss, grid->oSites(), {
auto cm = Umu_v[ss];
cm()()(2, x) = adj(cm()()(0, y) * cm()()(1, z) -
cm()()(0, z) * cm()()(1, y)); // x= yz-zy
cm()()(2, y) = adj(cm()()(0, z) * cm()()(1, x) -
cm()()(0, x) * cm()()(1, z)); // y= zx-xz
cm()()(2, z) = adj(cm()()(0, x) * cm()()(1, y) -
cm()()(0, y) * cm()()(1, x)); // z= xy-yx
Umu_v[ss] = cm;
});
}
static void ProjectSU3(Lattice<iVector<iScalar<iMatrix<vComplexD, 3> >, Nd> > &U)
{
GridBase *grid = U.Grid();
// Reunitarise
for (int mu = 0; mu < Nd; mu++) {
auto Umu = PeekIndex<LorentzIndex>(U, mu);
Umu = ProjectOnGroup(Umu);
ProjectSU3(Umu);
PokeIndex<LorentzIndex>(U, Umu, mu);
}
}
NAMESPACE_END(Grid);
#endif