LindhardSusceptibilityCalculator.h

/* Copyright 2017 Kristofer Björnson
 *
 * 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.
 */


#ifndef COM_DAFER45_TBTK_LINDHARD_SUSCEPTIBILITY_CALCULATOR
#define COM_DAFER45_TBTK_LINDHARD_SUSCEPTIBILITY_CALCULATOR

#include "TBTK/RPA/MomentumSpaceContext.h"
#include "TBTK/RPA/SusceptibilityCalculator.h"

#include <complex>

//#include <omp.h>

namespace TBTK{

class LindhardSusceptibilityCalculator : public SusceptibilityCalculator{
public:
    LindhardSusceptibilityCalculator(
        const RPA::MomentumSpaceContext &momentumSpaceContext
    );

    virtual ~LindhardSusceptibilityCalculator();

    virtual LindhardSusceptibilityCalculator* createSlave();

    virtual std::complex<double> calculateSusceptibility(
        const std::vector<double> &k,
        const std::vector<int> &orbitalIndices,
        std::complex<double> energy
    );

    virtual std::vector<std::complex<double>> calculateSusceptibility(
        const DualIndex &kDual,
        const std::vector<int> &orbitalIndices
    );

    void precompute(unsigned int numWorkers = 129);

    void setSusceptibilityIsSafeFromPoles(
        bool susceptibilityIsSafeFromPoles
    );

    bool getSusceptibilityIsSafeFromPoles() const;
private:
    bool susceptibilityIsSafeFromPoles;

    double *fermiDiracLookupTable;

    LindhardSusceptibilityCalculator(
        const RPA::MomentumSpaceContext &momentumSpaceContext,
        int *kPlusQLookupTable,
        double *fermiDiracLookupTable
    );

    std::complex<double> calculateSusceptibilityLindhard(
        const std::vector<double> &k,
        const std::vector<int> &orbitalIndices,
        std::complex<double> energy
    );

    template<bool useKPlusQLookupTable, bool isSafeFromPoles>
    std::vector<std::complex<double>> calculateSusceptibilityLindhard(
        const DualIndex &kDual,
        const std::vector<int> &orbitalIndices
    );

    std::complex<double> getPoleTimesTwoFermi(
        std::complex<double> energy,
        double e2,
        double e1,
        double chemicalPotential,
        double temperature,
        int kPlusQLinearIndex,
        unsigned int meshPoint,
        unsigned int state2,
        unsigned int state1,
        unsigned int numOrbitals
    ) const;
};

inline void LindhardSusceptibilityCalculator::setSusceptibilityIsSafeFromPoles(
    bool susceptibilityIsSafeFromPoles
){
    this->susceptibilityIsSafeFromPoles = susceptibilityIsSafeFromPoles;
}

inline bool LindhardSusceptibilityCalculator::getSusceptibilityIsSafeFromPoles() const{
    return susceptibilityIsSafeFromPoles;
}

};  //End of namespace TBTK

#endif