CCSDEnergyCalculation.hpp

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// This file is part of GQCG-GQCP.
//
// Copyright (C) 2017-2020  the GQCG developers
//
// GQCG-GQCP is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// GQCG-GQCP is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with GQCG-GQCP.  If not, see <http://www.gnu.org/licenses/>.
 
#pragma once
 
 
#include "Mathematical/Algorithm/Step.hpp"
#include "QCMethod/CC/CCSDEnvironment.hpp"
 
 
namespace GQCP {
 
 
template <typename _Scalar>
class CCSDEnergyCalculation:
    public Step<CCSDEnvironment<_Scalar>> {
 
public:
    using Scalar = _Scalar;
    using Environment = CCSDEnvironment<Scalar>;
 
 
public:
    /*
     *  PUBLIC OVERRIDDEN METHODS
     */
 
    std::string description() const override {
        return "Calculate the current CCSD electronic correlation energy.";
    }
 
 
    void execute(Environment& environment) override {
 
        // Prepare some variables.
        const auto& f = environment.f;
        const auto& V_A = environment.V_A;
        const auto& t1 = environment.t1_amplitudes.back();
        const auto& t2 = environment.t2_amplitudes.back();
 
        // Calculate the current correlation energy and push it to the environment.
        const auto current_correlation_energy = QCModel::CCSD<Scalar>::calculateCorrelationEnergy(f, V_A, t1, t2);
        environment.correlation_energies.push_back(current_correlation_energy);
    }
};
 
 
}  // namespace GQCP