LibcintTwoElectronIntegralBuffer.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/BaseTwoElectronIntegralBuffer.hpp"
 
 
namespace GQCP {
 
 
template <typename _IntegralScalar, size_t _N>
class LibcintTwoElectronIntegralBuffer: public BaseTwoElectronIntegralBuffer<_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:
    std::vector<IntegralScalar> buffer;  // the libcint integral data converted to a C++ vector
 
    int result;  // the result of the libcint_function call
 
 
public:
    /*
     *  CONSTRUCTORS
     */
 
    LibcintTwoElectronIntegralBuffer(const std::vector<IntegralScalar>& buffer, const size_t nbf1, const size_t nbf2, const size_t nbf3, const size_t nbf4, const int result) :
        buffer {buffer},
        result {result},
        BaseTwoElectronIntegralBuffer<IntegralScalar, N>(nbf1, nbf2, nbf3, nbf4) {}
 
 
    /*
     *  PUBLIC OVERRIDDEN METHODS
     */
 
    bool areIntegralsAllZero() const override { return (result == 0); }
 
    IntegralScalar value(const size_t i, const size_t f1, const size_t f2, const size_t f3, const size_t f4) const override {
        return this->buffer[f1 + this->nbf1 * (f2 + this->nbf2 * (f3 + this->nbf3 * (f4 + this->nbf4 * i)))];  // column major for libcint
    }
};
 
 
}  // namespace GQCP