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https://github.com/triqs/dft_tools
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103 lines
3.5 KiB
C++
103 lines
3.5 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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#pragma once
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#include "brillouin_zone.hpp"
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#include <triqs/utility/complex_ops.hpp>
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namespace triqs {
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namespace lattice {
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/**
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For tightbinding Hamiltonian with fully localised orbitals
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Overlap between orbital is taken as unit matrix.
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*/
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class tight_binding {
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bravais_lattice bl_;
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std::vector<std::vector<long>> all_disp;
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std::vector<matrix<dcomplex>> all_matrices;
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public:
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///
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tight_binding(bravais_lattice const& bl, std::vector<std::vector<long>> all_disp, std::vector<matrix<dcomplex>> all_matrices);
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tight_binding() = default;
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/// Underlying lattice
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bravais_lattice const& lattice() const { return bl_; }
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/// Number of bands, i.e. size of the matrix t(k)
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int n_bands() const { return bl_.n_orbitals(); }
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// calls F(R, t(R)) for all R
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template <typename F> friend void foreach(tight_binding const& tb, F f) {
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int n = tb.all_disp.size();
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for (int i = 0; i < n; ++i) f(tb.all_disp[i], tb.all_matrices[i]);
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}
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// a simple function on the domain brillouin_zone
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struct fourier_impl {
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tight_binding const& tb;
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const int nb;
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using domain_t = brillouin_zone;
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brillouin_zone domain() const {
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return {tb.lattice()};
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}
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template <typename K> matrix<dcomplex> operator()(K const& k) {
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matrix<dcomplex> res(nb, nb);
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res() = 0;
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foreach(tb, [&](std::vector<long> const& displ, matrix<dcomplex> const& m) {
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double dot_prod = 0;
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int imax = displ.size();
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for (int i = 0; i < imax; ++i) dot_prod += k(i) * displ[i];
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//double dot_prod = k(0) * displ[0] + k(1) * displ[1];
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res += m * exp(2_j * M_PI * dot_prod);
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});
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return res;
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}
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};
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fourier_impl friend fourier(tight_binding const& tb) {
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return {tb, tb.n_bands()};
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}
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}; // tight_binding
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/**
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Factorized version of hopping (for speed)
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k_in[:,n] is the nth vector
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In the result, R[:,:,n] is the corresponding hopping t(k)
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*/
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array<dcomplex, 3> hopping_stack(tight_binding const& TB, arrays::array_const_view<double, 2> k_stack);
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// not optimal ordering here
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std::pair<array<double, 1>, array<double, 2>> dos(tight_binding const& TB, int nkpts, int neps);
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std::pair<array<double, 1>, array<double, 1>> dos_patch(tight_binding const& TB, const array<double, 2>& triangles, int neps,
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int ndiv);
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array<double, 2> energies_on_bz_path(tight_binding const& TB, k_t const& K1, k_t const& K2, int n_pts);
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array<dcomplex, 3> energy_matrix_on_bz_path(tight_binding const& TB, k_t const& K1, k_t const& K2, int n_pts);
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array<double, 2> energies_on_bz_grid(tight_binding const& TB, int n_pts);
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}
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}
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