LibcintOneElectronIntegralBuffer.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 "Basis/Integrals/BaseOneElectronIntegralBuffer.hpp"
 
 
namespace GQCP {
 
 
template <typename _IntegralScalar, size_t _N>
class LibcintOneElectronIntegralBuffer: public BaseOneElectronIntegralBuffer<_IntegralScalar, _N> {
public:
    using IntegralScalar = _IntegralScalar;  // the scalar representation of an integral
    static constexpr auto N = _N;            // the number of components the operator has
 
 
private:
    double scaling_factor;               // a factor that multiplies every calculated value (for example in the dipole integrals, an extra factor -1 should be included)
    std::vector<IntegralScalar> buffer;  // the libcint integral data converted to a C++ vector
 
    int result;  // the result of the libcint_function call
 
 
public:
    /*
     *  CONSTRUCTORS
     */
 
    LibcintOneElectronIntegralBuffer(const std::vector<IntegralScalar>& buffer, const size_t nbf1, const size_t nbf2, const int result, const double scaling_factor = 1.0) :
        scaling_factor {scaling_factor},
        buffer {buffer},
        result {result},
        BaseOneElectronIntegralBuffer<IntegralScalar, N>(nbf1, nbf2) {}
 
 
    /*
     *  PUBLIC OVERRIDDEN METHODS
     */
 
    bool areIntegralsAllZero() const override { return (this->result == 0); }
 
    IntegralScalar value(const size_t i, const size_t f1, const size_t f2) const override {
        return this->scaling_factor * this->buffer[f1 + this->nbf1 * (f2 + this->nbf2 * i)];  // column-major ordering for libcint
    }
};
 
 
}  // namespace GQCP