superlattice.hpp

#pragma once
 
#include "./fourier_polynomial.hpp"
#include "../../utility/macros.hpp"
 
#include <nda/nda.hpp>
 
#include <optional>
 
namespace triqs::experimental::lattice {

 
  // --------------------------------------------------
  class superlattice {
    nda::matrix<long> units;            // Unit vector of the superlattice units[a, _] = unit vector a
    nda::array<long, 2> cluster_points; // Cluster: set of points in original lattice coordinate
    //  NB : in d = 2, we don't use the third component.
    nda::matrix<double> transfo_SL_L; // Transformation matrix SL -> L: = inverse(transpose(units))
    long _dim = units.extent(0);      // Dimension of the superlattice
 
    public:
    superlattice(nda::array<long, 2> sl_units, nda::array<long, 2> cluster_pts);

    C2PY_IGNORE auto const &get_sl_units() const { return units; }

    C2PY_IGNORE auto const &get_cluster_pts() const { return cluster_points; }

    long dim() const { return _dim; }

    long n_cluster_sites() const { return cluster_points.extent(0); }

    C2PY_IGNORE std::optional<nda::vector<long>> L_to_SL(nda::vector<long> const &r_l, double epsilon = 1.e-12) const;
  };
 
  // --------------------------------------------------

  template <int kdim> fourier_polynomial<2, kdim> fold(superlattice const &sl, fourier_polynomial<2, kdim> const &fp);

 
} // namespace triqs::experimental::lattice