mirror of
https://github.com/triqs/dft_tools
synced 2024-11-01 11:43:47 +01:00
235 lines
9.0 KiB
C++
235 lines
9.0 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_base.hpp"
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#include "fourier_matsubara.hpp"
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#include <fftw3.h>
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namespace triqs {
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namespace gfs {
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template <typename GfElementType> GfElementType convert_green(dcomplex const& x) { return x; }
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template <> double convert_green<double>(dcomplex const& x) { return real(x); }
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//--------------------------------------------------------------------------------------
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struct impl_worker {
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arrays::vector<dcomplex> g_in, g_out;
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dcomplex oneFermion(dcomplex a, double b, double tau, double beta) {
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return -a * (b >= 0 ? exp(-b * tau) / (1 + exp(-beta * b)) : exp(b * (beta - tau)) / (1 + exp(beta * b)));
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}
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dcomplex oneBoson(dcomplex a, double b, double tau, double beta) {
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return a * (b >= 0 ? exp(-b * tau) / (exp(-beta * b) - 1) : exp(b * (beta - tau)) / (1 - exp(b * beta)));
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}
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//-------------------------------------
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void direct(gf_view<imfreq, scalar_valued> gw, gf_const_view<imtime, scalar_valued> gt) {
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auto ta = gt(freq_infty());
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direct_impl(make_gf_view_without_tail(gw), make_gf_view_without_tail(gt), ta);
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gw.singularity() = gt.singularity(); // set tail
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}
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void direct(gf_view<imfreq, scalar_valued, no_tail> gw, gf_const_view<imtime, scalar_valued, no_tail> gt) {
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auto ta = local::tail{1,1};
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direct_impl(gw, gt, ta);
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}
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//-------------------------------------
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private:
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void direct_impl(gf_view<imfreq, scalar_valued, no_tail> gw, gf_const_view<imtime, scalar_valued, no_tail> gt,
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local::tail const& ta) {
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// TO BE MODIFIED AFTER SCALAR IMPLEMENTATION TODO
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dcomplex d = ta(1)(0, 0), A = ta.get_or_zero(2)(0, 0), B = ta.get_or_zero(3)(0, 0);
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double b1 = 0, b2 = 0, b3 = 0;
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dcomplex a1, a2, a3;
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double beta = gt.mesh().domain().beta;
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auto L = (gt.mesh().kind() == full_bins ? gt.mesh().size() - 1 : gt.mesh().size());
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double fact = beta / gt.mesh().size();
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dcomplex iomega = dcomplex(0.0, 1.0) * std::acos(-1) / beta;
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dcomplex iomega2 = iomega * 2 * gt.mesh().delta() * (gt.mesh().kind() == half_bins ? 0.5 : 0.0);
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g_in.resize(gt.mesh().size());
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g_out.resize(gw.mesh().size());
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if (gw.domain().statistic == Fermion) {
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b1 = 0;
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b2 = 1;
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b3 = -1;
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a1 = d - B;
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a2 = (A + B) / 2;
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a3 = (B - A) / 2;
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} else {
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b1 = -0.5;
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b2 = -1;
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b3 = 1;
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a1 = 4 * (d - B) / 3;
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a2 = B - (d + A) / 2;
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a3 = d / 6 + A / 2 + B / 3;
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}
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if (gw.domain().statistic == Fermion) {
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for (auto& t : gt.mesh())
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g_in[t.index()] = fact * exp(iomega * t) *
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(gt[t] - (oneFermion(a1, b1, t, beta) + oneFermion(a2, b2, t, beta) + oneFermion(a3, b3, t, beta)));
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} else {
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for (auto& t : gt.mesh())
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g_in[t.index()] = fact * (gt[t] - (oneBoson(a1, b1, t, beta) + oneBoson(a2, b2, t, beta) + oneBoson(a3, b3, t, beta)));
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}
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details::fourier_base(g_in, g_out, L, true);
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for (auto& w : gw.mesh()) {
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gw[w] = g_out(w.index()) * exp(iomega2 * w.index()) + a1 / (w - b1) + a2 / (w - b2) + a3 / (w - b3);
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}
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}
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public:
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//-------------------------------------
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void inverse(gf_view<imtime, scalar_valued> gt, gf_const_view<imfreq, scalar_valued> gw) {
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static bool Green_Function_Are_Complex_in_time = false;
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// If the Green function are NOT complex, then one use the symmetry property
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// fold the sum and get a factor 2
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auto ta = gw(freq_infty());
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// TO BE MODIFIED AFTER SCALAR IMPLEMENTATION TODO
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dcomplex d = ta(1)(0, 0), A = ta.get_or_zero(2)(0, 0), B = ta.get_or_zero(3)(0, 0);
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double b1, b2, b3;
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dcomplex a1, a2, a3;
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double beta = gw.domain().beta;
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size_t L = gt.mesh().size() - (gt.mesh().kind() == full_bins ? 1 : 0); // L can be different from gt.mesh().size() (depending
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// on the mesh kind) and is given to the FFT algorithm
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dcomplex iomega = dcomplex(0.0, 1.0) * std::acos(-1) / beta;
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dcomplex iomega2 = -iomega * 2 * gt.mesh().delta() * (gt.mesh().kind() == half_bins ? 0.5 : 0.0);
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double fact = (Green_Function_Are_Complex_in_time ? 1 : 2) / beta;
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g_in.resize(gw.mesh().size());
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g_out.resize(gt.mesh().size());
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if (gw.domain().statistic == Fermion) {
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b1 = 0;
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b2 = 1;
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b3 = -1;
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a1 = d - B;
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a2 = (A + B) / 2;
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a3 = (B - A) / 2;
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} else {
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b1 = -0.5;
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b2 = -1;
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b3 = 1;
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a1 = 4 * (d - B) / 3;
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a2 = B - (d + A) / 2;
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a3 = d / 6 + A / 2 + B / 3;
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}
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g_in() = 0;
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for (auto& w : gw.mesh()) {
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g_in[w.index()] = fact * exp(w.index() * iomega2) * (gw[w] - (a1 / (w - b1) + a2 / (w - b2) + a3 / (w - b3)));
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}
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// for bosons GF(w=0) is divided by 2 to avoid counting it twice
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if (gw.domain().statistic == Boson && !Green_Function_Are_Complex_in_time) g_in(0) *= 0.5;
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details::fourier_base(g_in, g_out, L, false);
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// CORRECT FOR COMPLEX G(tau) !!!
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typedef double gt_result_type;
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// typedef typename gf<imtime>::mesh_type::gf_result_type gt_result_type;
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if (gw.domain().statistic == Fermion) {
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for (auto& t : gt.mesh()) {
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gt[t] =
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convert_green<gt_result_type>(g_out(t.index() == L ? 0 : t.index()) * exp(-iomega * t) + oneFermion(a1, b1, t, beta) +
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oneFermion(a2, b2, t, beta) + oneFermion(a3, b3, t, beta));
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}
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} else {
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for (auto& t : gt.mesh())
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gt[t] = convert_green<gt_result_type>(g_out(t.index() == L ? 0 : t.index()) + oneBoson(a1, b1, t, beta) +
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oneBoson(a2, b2, t, beta) + oneBoson(a3, b3, t, beta));
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}
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double pm = (gw.domain().statistic == Fermion ? -1.0 : 1.0);
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if (gt.mesh().kind() == full_bins) gt.on_mesh(L) = pm * (gt.on_mesh(0) + convert_green<gt_result_type>(ta(1)(0, 0)));
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// set tail
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gt.singularity() = gw.singularity();
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}
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}; // class worker
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//--------------------------------------------
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template <typename Opt>
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void fourier_impl(gf_view<imfreq, scalar_valued, Opt> gw, gf_const_view<imtime, scalar_valued, Opt> gt) {
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impl_worker w;
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w.direct(gw, gt);
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}
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template <typename Opt>
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void fourier_impl(gf_view<imfreq, matrix_valued, Opt> gw, gf_const_view<imtime, matrix_valued, Opt> gt) {
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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 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<imtime, scalar_valued> gt, gf_const_view<imfreq, scalar_valued> gw) {
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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<imtime, matrix_valued> gt, gf_const_view<imfreq, matrix_valued> gw) {
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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 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<imfreq, scalar_valued> g,
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gf_keeper<tags::fourier, imtime, scalar_valued> const& L) {
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fourier_impl(g, L.g);
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}
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void triqs_gf_view_assign_delegation(gf_view<imfreq, matrix_valued> g,
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gf_keeper<tags::fourier, imtime, matrix_valued> const& L) {
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fourier_impl(g, L.g);
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}
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void triqs_gf_view_assign_delegation(gf_view<imtime, scalar_valued> g,
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gf_keeper<tags::fourier, imfreq, scalar_valued> const& L) {
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inverse_fourier_impl(g, L.g);
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}
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void triqs_gf_view_assign_delegation(gf_view<imtime, matrix_valued> g,
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gf_keeper<tags::fourier, imfreq, matrix_valued> const& L) {
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inverse_fourier_impl(g, L.g);
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}
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void triqs_gf_view_assign_delegation(gf_view<imfreq, scalar_valued, no_tail> g,
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gf_keeper<tags::fourier, imtime, scalar_valued, no_tail> const& L) {
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fourier_impl(g, L.g);
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}
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void triqs_gf_view_assign_delegation(gf_view<imfreq, matrix_valued, no_tail> g,
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gf_keeper<tags::fourier, imtime, matrix_valued, no_tail> const& L) {
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fourier_impl(g, L.g);
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}
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}
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}
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