mirror of
https://github.com/triqs/dft_tools
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246 lines
8.8 KiB
C++
246 lines
8.8 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 "tight_binding.hpp"
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#include <triqs/arrays/algorithms.hpp>
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#include <triqs/arrays/linalg/eigenelements.hpp>
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#include "grid_generator.hpp"
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namespace triqs {
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namespace lattice {
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using namespace arrays;
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tight_binding::tight_binding(bravais_lattice const& bl, std::vector<std::vector<long>> all_disp,
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std::vector<matrix<dcomplex>> all_matrices)
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: bl_(bl), all_disp(std::move(all_disp)), all_matrices(std::move(all_matrices)) {
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// checking inputs
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if (all_disp.size() != all_matrices.size()) TRIQS_RUNTIME_ERROR << " Number of displacements != Number of matrices";
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for (int i = 0; i < all_disp.size(); ++i) {
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if (all_disp[i].size() != bl_.dim())
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TRIQS_RUNTIME_ERROR << "displacement of incorrect size : got " << all_disp[i].size() << "instead of " << bl_.dim();
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if (first_dim(all_matrices[i]) != n_bands())
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TRIQS_RUNTIME_ERROR << "the first dim matrix is of size " << first_dim(all_matrices[i]) << " instead of " << n_bands();
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if (second_dim(all_matrices[i]) != n_bands())
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TRIQS_RUNTIME_ERROR << "the second dim matrix is of size " << second_dim(all_matrices[i]) << " instead of " << n_bands();
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}
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}
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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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auto TK = fourier(TB);
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array<dcomplex, 3> res(TB.n_bands(), TB.n_bands(), k_stack.shape(1));
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for (int i = 0; i < k_stack.shape(1); ++i) res(range(), range(), i) = TK(k_stack(range(), i));
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return res;
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}
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//------------------------------------------------------
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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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auto TK = fourier(TB);
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int norb = TB.lattice().n_orbitals();
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int ndim = TB.lattice().dim();
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array<double, 2> eval(norb, n_pts);
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k_t dk = (K2 - K1) / double(n_pts), k = K1;
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for (int i = 0; i < n_pts; ++i, k += dk) {
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eval(range(), i) = linalg::eigenvalues(TK(k(range(0, ndim)))());
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}
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return eval;
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}
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//------------------------------------------------------
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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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auto TK = fourier(TB);
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int norb = TB.lattice().n_orbitals();
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int ndim = TB.lattice().dim();
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array<dcomplex, 3> eval(norb,norb,n_pts);
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k_t dk = (K2 - K1) / double(n_pts), k = K1;
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for (int i = 0; i < n_pts; ++i, k += dk) {
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eval(range(),range(),i) = TK(k(range(0, ndim)))();
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}
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return eval;
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}
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//------------------------------------------------------
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array<double, 2> energies_on_bz_grid(tight_binding const& TB, int n_pts) {
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auto TK = fourier(TB);
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int norb = TB.lattice().n_orbitals();
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int ndim = TB.lattice().dim();
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grid_generator grid(ndim, n_pts);
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array<double, 2> eval(norb, grid.size());
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for (; grid; ++grid) {
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eval(range(), grid.index()) = linalg::eigenvalues(TK((*grid)(range(0, ndim)))());
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}
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return eval;
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}
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//------------------------------------------------------
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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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// The fourier transform of TK
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auto TK = fourier(TB);
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// loop on the BZ
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int ndim = TB.lattice().dim();
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int norb = TB.lattice().n_orbitals();
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grid_generator grid(ndim, nkpts);
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array<double, 1> tempeval(norb);
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array<dcomplex, 3> evec(norb, norb, grid.size());
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array<double, 2> eval(norb, grid.size());
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if (norb == 1)
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for (; grid; ++grid) {
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double ee = real(TK((*grid)(range(0, ndim)))(0, 0));
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eval(0, grid.index()) = ee;
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evec(0, 0, grid.index()) = 1;
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}
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else
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for (; grid; ++grid) {
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// cerr<<" index = "<<grid.index()<<endl;
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array_view<double, 1> eval_sl = eval(range(), grid.index());
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array_view<dcomplex, 2> evec_sl = evec(range(), range(), grid.index());
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std::tie(eval_sl, evec_sl) = linalg::eigenelements(TK((*grid)(range(0, ndim)))); //, true);
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// cerr<< " point "<< *grid << " value "<< eval_sl<< endl; //" "<< (*grid) (range(0,ndim)) << endl;
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}
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// define the epsilon mesh, etc.
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array<double, 1> epsilon(neps);
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double epsmax = max_element(eval);
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double epsmin = min_element(eval);
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double deps = (epsmax - epsmin) / neps;
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// for (int i =0; i< neps; ++i) epsilon(i)= epsmin+i/(neps-1.0)*(epsmax-epsmin);
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for (int i = 0; i < neps; ++i) epsilon(i) = epsmin + (i + 0.5) * deps;
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// bin the eigenvalues according to their energy
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// NOTE: a is defined as an integer. it is the index for the DOS.
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// REPORT <<"Starting Binning ...."<<endl;
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array<double, 2> rho(neps, norb);
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rho() = 0;
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for (int l = 0; l < norb; l++) {
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for (int j = 0; j < grid.size(); j++) {
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int a = int((eval(l, j) - epsmin) / deps);
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if (a == int(neps)) a = a - 1;
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for (int k = 0; k < norb; k++) {
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rho(a, l) += real(conj(evec(l, k, j)) * evec(l, k, j));
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}
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}
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}
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rho /= grid.size() * deps;
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return std::make_pair(epsilon, rho);
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}
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//----------------------------------------------------------------------------------
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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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// WARNING: This version only works for a single band Hamiltonian in 2 dimensions!!!!
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// triangles is an array of points defining the triangles of the patch
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// neps in the number of bins in energy
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// ndiv in the number of divisions used to divide the triangles
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// int ndim=TB.lattice().dim();
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// int norb=TB.lattice().n_orbitals();
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int ntri = triangles.shape(0) / 3;
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array<double, 1> dos(neps);
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// Check consistency
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int ndim = TB.lattice().dim();
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// int norb=TB.lattice().n_orbitals();
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if (ndim != 2) TRIQS_RUNTIME_ERROR << "dos_patch : dimension 2 only !";
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if (triangles.shape(1) != ndim)
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TRIQS_RUNTIME_ERROR << "dos_patch : the second dimension of the 'triangle' array in not " << ndim;
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// Every triangle has ndiv*ndiv k points
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int nk = ntri * ndiv * ndiv;
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int k_index = 0;
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double epsmax = -100000, epsmin = 100000;
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array<dcomplex, 2> thop(1, 1);
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array<double, 1> energ(nk), weight(nk);
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// a, b, c are the corners of the triangle
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// g the center of gravity taken from a
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array<double, 1> a(ndim), b(ndim), c(ndim), g(ndim), rv(ndim);
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int pt = 0;
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double s, t;
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// The fourier transform of TK
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auto TK = fourier(TB);
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// loop over the triangles
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for (int tri = 0; tri < ntri; tri++) {
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a = triangles(pt, range());
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pt++;
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b = triangles(pt, range());
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pt++;
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c = triangles(pt, range());
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pt++;
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g = ((a + b + c) / 3.0 - a) / double(ndiv);
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// the area around a k point might be different from one triangle to the other
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// so I use it to weight the sum in the dos
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double area = abs(0.5 * ((b(0) - a(0)) * (c(1) - a(1)) - (b(1) - a(1)) * (c(0) - a(0))) / (ndiv * ndiv));
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for (int i = 0; i < ndiv; i++) {
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s = i / double(ndiv);
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for (int j = 0; j < ndiv - i; j++) {
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t = j / double(ndiv);
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for (int k = 0; k < 2; k++) {
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rv = a + s * (b - a) + t * (c - a) + (k + 1.0) * g;
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if (k == 0 || j < ndiv - i - 1) {
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energ(k_index) = real(TK(rv)(0, 0));
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// compute(rv);
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// energ(k_index) = real(tk_for_eval(1,1)); //tk_for_eval is Fortran array
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weight(k_index) = area;
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if (energ(k_index) > epsmax) epsmax = energ(k_index);
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if (energ(k_index) < epsmin) epsmin = energ(k_index);
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k_index++;
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}
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}
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}
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}
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}
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// check consistency
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assert(k_index == nk);
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// define the epsilon mesh, etc.
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array<double, 1> epsilon(neps);
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double deps = (epsmax - epsmin) / neps;
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for (int i = 0; i < neps; ++i) epsilon(i) = epsmin + i / (neps - 1.0) * (epsmax - epsmin);
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// bin the eigenvalues according to their energy
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int ind;
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double totalweight(0.0);
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dos() = 0.0;
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for (int j = 0; j < nk; j++) {
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ind = int((energ(j) - epsmin) / deps);
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if (ind == int(neps)) ind--;
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dos(ind) += weight(j);
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totalweight += weight(j);
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}
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dos /= deps; // Normalize the DOS
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return {std::move(epsilon), std::move(dos)};
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}
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}
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}
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