bsecoupling.h

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/*
 *            Copyright 2009-2020 The VOTCA Development Team
 *                       (http://www.votca.org)
 *
 *      Licensed under the Apache License, Version 2.0 (the "License")
 *
 * You may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *              http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */
 
#pragma once
#ifndef VOTCA_XTP_BSECOUPLING_H
#define VOTCA_XTP_BSECOUPLING_H
 
// Local VOTCA includes
#include "couplingbase.h"
#include "qmstate.h"
 
namespace votca {
namespace xtp {
 
class BSECoupling : public CouplingBase {
 public:
  void Initialize(tools::Property& options) override;
  std::string Identify() const { return "bsecoupling"; }
 
  void Addoutput(tools::Property& type_summary, const Orbitals& orbitalsA,
                 const Orbitals& orbitalsB) const override;
 
  void CalculateCouplings(const Orbitals& orbitalsA, const Orbitals& orbitalsB,
                          const Orbitals& orbitalsAB) override;
 
 private:
  void WriteToProperty(tools::Property& summary, const QMState& stateA,
                       const QMState& stateB) const;
 
  double getSingletCouplingElement(Index levelA, Index levelB,
                                   Index methodindex) const;
 
  double getTripletCouplingElement(Index levelA, Index levelB,
                                   Index methodindex) const;
 
  Eigen::MatrixXd SetupCTStates(Index bseA_vtotal, Index bseB_vtotal,
                                Index bseAB_vtotal, Index bseAB_ctotal,
                                const Eigen::MatrixXd& A_AB,
                                const Eigen::MatrixXd& B_AB) const;
 
  Eigen::MatrixXd ProjectFrenkelExcitons(const Eigen::MatrixXd& BSE_Coeffs,
                                         const Eigen::MatrixXd& X_AB,
                                         Index bseX_vtotal, Index bseX_ctotal,
                                         Index bseAB_vtotal,
                                         Index bseAB_ctotal) const;
 
  template <class BSE_OPERATOR>
  std::array<Eigen::MatrixXd, 2> ProjectExcitons(Eigen::MatrixXd& FE_AB,
                                                 Eigen::MatrixXd& CTStates,
                                                 BSE_OPERATOR H) const;
  template <class BSE_OPERATOR>
  Eigen::MatrixXd CalcJ_dimer(BSE_OPERATOR& H,
                              Eigen::MatrixXd& projection) const;
 
  Eigen::MatrixXd OrthogonalizeCTs(Eigen::MatrixXd& FE_AB,
                                   Eigen::MatrixXd& CTStates) const;
 
  Eigen::MatrixXd Fulldiag(const Eigen::MatrixXd& J_dimer) const;
 
  Eigen::MatrixXd Perturbation(const Eigen::MatrixXd& J_dimer) const;
 
  std::array<Eigen::MatrixXd, 2> JAB_singlet;
  std::array<Eigen::MatrixXd, 2> JAB_triplet;
 
  bool doTriplets_;
  bool doSinglets_;
  bool output_perturbation_;
  Index levA_;
  Index levB_;
  Index occA_;
  Index unoccA_;
  Index occB_;
  Index unoccB_;
};
 
}  // namespace xtp
}  // namespace votca
 
#endif  // VOTCA_XTP_BSECOUPLING_H