McMurchieDavidsonCoefficient.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/Representation/Matrix.hpp"
 
 
namespace GQCP {
 
 
class McMurchieDavidsonCoefficient {
private:
    // One of the Cartesian components of the center of the left Cartesian GTO.
    double K;
 
    // One of the Cartesian components of the center of the right Cartesian GTO.
    double L;
 
    // The Gaussian exponent of the left Cartesian GTO.
    double a;
 
    // The Gaussian exponent of the right Cartesian GTO.
    double b;
 
 
public:
    /*
     *  MARK: Constructors
     */
 
    McMurchieDavidsonCoefficient(const double K, const double a, const double L, const double b);
 
 
    /*
     *  MARK: McMurchie-Davidson behavior
     */
 
    double operator()(const int i, const int j, const int t) const;
 
 
    /*
     *  MARK: Gaussian overlap behavior
     */
 
    double centerOfMass() const;
 
    double reducedExponent() const;
 
    double totalExponent() const { return a + b; }
 
    double distance() const { return this->K - this->L; }
};
 
 
}  // namespace GQCP