Program Listing for File spinhalfSC.hpp

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#pragma once
#include "models/fermionBasis.hpp"
#include "nrgcore/qOperator.hpp"
#include "nrgcore/qsymmetry.hpp"
#include "utils/qmatrix.hpp"
#include <algorithm>
#include <cmath>
#include <iostream>
#include <iterator>
#include <map>
#include <numeric>
#include <optional>
#include <string>
#include <tuple>
#include <vector>
class spinhalfSC {
  std::vector<qmatrix<double>> f_dag_raw;
  fermionBasis                 localSCbabsis;

public:
  spinhalfSC(double teps, double tUint, double tmag) // NOLINT
      : localSCbabsis(2, fermionBasis::spinOnly) {
    double Uint           = tUint;
    double epsilon_d      = teps;
    double magnetic_field = tmag;
    //
    // create_basis();
    // set_foperator();
    // set_chi_Q();
    // create_hamiltonian();
    // localSCbabsis = fermionBasis(2, fermionBasis::spinOnly);
    // Number of fermion channels/spins
    f_dag_operator = localSCbabsis.get_f_dag_operator();
    f_dag_raw      = localSCbabsis.get_raw_f_dag_operator();
    // n_Q
    n_Q = localSCbabsis.get_unique_Qnumbers();
    // set chi_Q
    chi_Q.clear();
    for (auto ai : n_Q) {
      double t_charge = std::accumulate(ai.begin(), ai.end(), 0);
      chi_Q.push_back(std::pow(-1., t_charge));
    }
    // std::cout << "chi_Q: " << chi_Q << std::endl;
    // set up the Hamiltonian
    auto n_up   = f_dag_raw[0].dot(f_dag_raw[0].cTranspose());
    auto n_down = f_dag_raw[1].dot(f_dag_raw[1].cTranspose());
    // std::cout << "n_up" << n_up << "n_down" << n_down;
    auto H = (n_up + n_down) * epsilon_d        // onsite energy
             + (n_up - n_down) * magnetic_field // Magnetic Field
             + (n_up.dot(n_down)) * Uint;       // Columb Energy
    // get the hamiltonian  in the blocked structure
    auto h_blocked = localSCbabsis.get_block_Hamiltonian(H);
    //  h_blocked.display();
    // Diagonalize the hamilton
    eigenvalues_Q.clear();
    eigenvalues_Q.resize(n_Q.size(), {});
    for (size_t i = 0; i < n_Q.size(); i++) {
      eigenvalues_Q[i] = (h_blocked.get(i, i)).value()->diag();
    }
    // TODO(sp): rotate the f operator
    // ####################################################################
    f_dag_operator =
        localSCbabsis.get_block_operators({f_dag_raw[0], f_dag_raw[1]});
    std::cout << "f_dag_operators: " << f_dag_operator.size() << std::endl;
    std::vector<qOperator> topr(f_dag_operator.size(), qOperator());
    for (size_t ip = 0; ip < f_dag_operator.size(); ip++) {
      for (size_t i = 0; i < n_Q.size(); i++) {
        for (size_t j = 0; j < n_Q.size(); j++) {
          auto tfopr = f_dag_operator[ip].get(i, j);
          if (tfopr) {
            topr[ip].set((h_blocked.get(i, i))
                             .value()
                             ->cTranspose()
                             .dot(*tfopr.value())
                             .dot(*(h_blocked.get(j, j)).value()),
                         i, j);
          }
        }
      }
    }
    f_dag_operator = topr;
    // End of the constructor
  }
  //
  void addSCDelta(double delta) {
    auto H = (f_dag_raw[0].cTranspose().dot(f_dag_raw[1].cTranspose()) +
              f_dag_raw[1].dot(f_dag_raw[0])) *
             delta;
    auto h_blocked = localSCbabsis.get_block_Hamiltonian(H);
    //  h_blocked.display();
    // Diagonalize the hamilton
    eigenvalues_Q.clear();
    eigenvalues_Q.resize(n_Q.size(), {});
    for (size_t i = 0; i < n_Q.size(); i++) {
      eigenvalues_Q[i] = (h_blocked.get(i, i)).value()->diag();
    }
    // TODO(sp): rotate the f operator
    // ####################################################################
    f_dag_operator =
        localSCbabsis.get_block_operators({f_dag_raw[0], f_dag_raw[1]});
    std::cout << "f_dag_operators: " << f_dag_operator.size() << std::endl;
    std::vector<qOperator> topr(f_dag_operator.size(), qOperator());
    for (size_t ip = 0; ip < f_dag_operator.size(); ip++) {
      for (size_t i = 0; i < n_Q.size(); i++) {
        for (size_t j = 0; j < n_Q.size(); j++) {
          auto tfopr = f_dag_operator[ip].get(i, j);
          if (tfopr) {
            topr[ip].set((h_blocked.get(i, i))
                             .value()
                             ->cTranspose()
                             .dot(*tfopr.value())
                             .dot(*(h_blocked.get(j, j)).value()),
                         i, j);
          }
        }
      }
    }
    f_dag_operator = topr;
  }
  [[nodiscard]] std::vector<std::vector<int>> get_basis() const {
    return n_Q;
  }
  [[nodiscard]] std::vector<std::vector<double>> get_eigenvaluesQ() const {
    return eigenvalues_Q;
  }
  [[nodiscard]] std::vector<double> get_chi_Q() const {
    return chi_Q;
  }
  // protected:
  // functions
  void set_chi_Q();
  //
  std::vector<qOperator>           f_dag_operator;
  std::vector<std::vector<double>> eigenvalues_Q;
  std::vector<double>              chi_Q;
  std::vector<std::vector<int>>    n_Q;
};