mirror of
https://github.com/triqs/dft_tools
synced 2024-12-29 15:45:46 +01:00
151 lines
6.0 KiB
C++
151 lines
6.0 KiB
C++
/*******************************************************************************
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*
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* TRIQS: a Toolbox for Research in Interacting Quantum Systems
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*
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* Copyright (C) 2011 by M. Ferrero, O. Parcollet
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*
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* TRIQS is free software: you can redistribute it and/or modify it under the
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* terms of the GNU General Public License as published by the Free Software
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* Foundation, either version 3 of the License, or (at your option) any later
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* version.
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*
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* TRIQS is distributed in the hope that it will be useful, but WITHOUT ANY
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* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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* details.
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*
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* You should have received a copy of the GNU General Public License along with
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* TRIQS. If not, see <http://www.gnu.org/licenses/>.
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*
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******************************************************************************/
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#include "fourier_real.hpp"
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#include <fftw3.h>
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namespace triqs { namespace gfs {
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namespace {
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double pi = std::acos(-1);
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dcomplex I(0,1);
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inline dcomplex th_expo(double t, double a ) { return (t > 0 ? -I * exp(-a*t) : ( t < 0 ? 0 : -0.5 * I * exp(-a*t) ) ) ; }
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inline dcomplex th_expo_neg(double t, double a ) { return (t < 0 ? I * exp( a*t) : ( t > 0 ? 0 : 0.5 * I * exp( a*t) ) ) ; }
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inline dcomplex th_expo_inv(double w, double a ) { return 1./(w+I*a) ; }
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inline dcomplex th_expo_neg_inv(double w, double a ) { return 1./(w-I*a) ; }
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}
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struct impl_worker {
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tqa::vector<dcomplex> g_in, g_out;
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void direct (gf_view<refreq,scalar_valued> gw, gf_const_view<retime,scalar_valued> gt){
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size_t L = gt.mesh().size();
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if (gw.mesh().size() != L) TRIQS_RUNTIME_ERROR << "Meshes are different";
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double test = std::abs(gt.mesh().delta() * gw.mesh().delta() * L / (2*pi) -1);
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if (test > 1.e-10) TRIQS_RUNTIME_ERROR << "Meshes are not compatible";
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const double tmin = gt.mesh().x_min();
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const double wmin = gw.mesh().x_min();
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//a is a number very larger than delta_w and very smaller than wmax-wmin, used in the tail computation
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const double a = gw.mesh().delta() * sqrt( double(L) );
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auto ta = gt(freq_infty());
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g_in.resize(L);
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g_in() = 0;
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g_out.resize(L);
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dcomplex t1 = ta(1)(0,0), t2= ta.get_or_zero(2)(0,0);
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dcomplex a1 = (t1 + I * t2/a )/2., a2 = (t1 - I * t2/a )/2.;
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for (auto const & t : gt.mesh())
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g_in[t.index()] = (gt[t] - (a1*th_expo(t,a) + a2*th_expo_neg(t,a))) * std::exp(I*t*wmin);
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details::fourier_base(g_in, g_out, L, true);
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for (auto const & w : gw.mesh())
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gw[w] = gt.mesh().delta() * std::exp(I*(w-wmin)*tmin) * g_out(w.index())
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+ a1*th_expo_inv(w,a) + a2*th_expo_neg_inv(w,a);
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gw.singularity() = gt.singularity();// set tail
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}
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void inverse(gf_view<retime,scalar_valued> gt, gf_const_view<refreq,scalar_valued> gw){
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size_t L = gw.mesh().size();
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if ( L != gt.mesh().size()) TRIQS_RUNTIME_ERROR << "Meshes are different";
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double test = std::abs(gt.mesh().delta() * gw.mesh().delta() * L / (2*pi) -1);
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if (test > 1.e-10) TRIQS_RUNTIME_ERROR << "Meshes are not compatible";
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const double tmin = gt.mesh().x_min();
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const double wmin = gw.mesh().x_min();
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//a is a number very larger than delta_w and very smaller than wmax-wmin, used in the tail computation
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const double a = gw.mesh().delta() * sqrt( double(L) );
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auto ta = gw(freq_infty());
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tqa::vector<dcomplex> g_in(L), g_out(L);
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dcomplex t1 = ta(1)(0,0), t2 = ta.get_or_zero(2)(0,0);
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dcomplex a1 = (t1 + I * t2/a )/2., a2 = (t1 - I * t2/a )/2.;
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g_in() = 0;
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for (auto const & w: gw.mesh())
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g_in(w.index()) = (gw[w] - a1*th_expo_inv(w,a) - a2*th_expo_neg_inv(w,a) ) * std::exp(-I*w*tmin);
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details::fourier_base(g_in, g_out, L, false);
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const double corr = 1.0/(gt.mesh().delta()*L);
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for (auto const & t : gt.mesh())
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gt[t] = corr * std::exp(I*wmin*(tmin-t)) *
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g_out[ t.index() ] + a1 * th_expo(t,a) + a2 * th_expo_neg(t,a) ;
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// set tail
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gt.singularity() = gw.singularity();
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}
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};
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//--------------------------------------------------------------------------------------
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void fourier_impl(gf_view<refreq,scalar_valued> gw, gf_const_view<retime,scalar_valued> gt, scalar_valued){
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impl_worker w;
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w.direct(gw, gt);
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}
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void fourier_impl(gf_view<refreq,matrix_valued> gw, gf_const_view<retime,matrix_valued> gt, matrix_valued){
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impl_worker w;
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for (size_t n1=0; n1<gw.data().shape()[1];n1++)
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for (size_t n2=0; n2<gw.data().shape()[2];n2++) {
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auto gw_sl=slice_target_to_scalar(gw, n1, n2);
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auto gt_sl=slice_target_to_scalar(gt, n1, n2);
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w.direct(gw_sl, gt_sl);
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}
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}
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//---------------------------------------------------------------------------
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void inverse_fourier_impl (gf_view<retime,scalar_valued> gt, gf_const_view<refreq,scalar_valued> gw, scalar_valued){
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impl_worker w;
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w.inverse(gt,gw);
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}
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void inverse_fourier_impl (gf_view<retime,matrix_valued> gt, gf_const_view<refreq,matrix_valued> gw, matrix_valued){
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impl_worker w;
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for (size_t n1=0; n1<gt.data().shape()[1];n1++)
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for (size_t n2=0; n2<gt.data().shape()[2];n2++) {
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auto gt_sl=slice_target_to_scalar(gt, n1, n2);
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auto gw_sl=slice_target_to_scalar(gw, n1, n2);
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w.inverse(gt_sl, gw_sl);
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}
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}
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//---------------------------------------------------------------------------
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void triqs_gf_view_assign_delegation( gf_view<refreq,matrix_valued> g, gf_keeper<tags::fourier,retime,matrix_valued> const & L) { fourier_impl (g,L.g, matrix_valued());}
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void triqs_gf_view_assign_delegation( gf_view<refreq,scalar_valued> g, gf_keeper<tags::fourier,retime,scalar_valued> const & L) { fourier_impl (g,L.g, scalar_valued());}
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void triqs_gf_view_assign_delegation( gf_view<retime,matrix_valued> g, gf_keeper<tags::fourier,refreq,matrix_valued> const & L) { inverse_fourier_impl(g,L.g, matrix_valued());}
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void triqs_gf_view_assign_delegation( gf_view<retime,scalar_valued> g, gf_keeper<tags::fourier,refreq,scalar_valued> const & L) { inverse_fourier_impl(g,L.g, scalar_valued());}
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}}
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