SusceptibilityCalculator.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_SUSCEPTIBILITY_CALCULATOR
#define COM_DAFER45_TBTK_SUSCEPTIBILITY_CALCULATOR
 
#include "TBTK/RPA/DualIndex.h"
#include "TBTK/IndexedDataTree.h"
#include "TBTK/InteractionAmplitude.h"
#include "TBTK/RPA/MomentumSpaceContext.h"
#include "TBTK/Resource.h"
#include "TBTK/SerializableVector.h"
#include "TBTK/UnitHandler.h"
 
#include <complex>
#include <vector>
 
//#include <omp.h>
 
namespace TBTK{
 
class SusceptibilityCalculator{
public:
    enum Algorithm {
        Lindhard = 0,
        Matsubara = 1
    };
 
    SusceptibilityCalculator(
        Algorithm algorithm,
        const RPA::MomentumSpaceContext &momentumSpaceContext
    );
 
    virtual ~SusceptibilityCalculator();
 
    virtual SusceptibilityCalculator* createSlave() = 0;
 
    virtual std::complex<double> calculateSusceptibility(
        const std::vector<double> &k,
        const std::vector<int> &orbitalIndices,
        std::complex<double> energy
    ) = 0;
 
    virtual std::vector<std::complex<double>> calculateSusceptibility(
        const DualIndex &kDual,
        const std::vector<int> &orbitalIndices
    ) = 0;
 
    std::vector<std::complex<double>> calculateSusceptibility(
        const std::vector<double> &k,
        const std::vector<int> &orbitalIndices
    );
 
//  void precompute(unsigned int numWorkers = 129);
 
    const RPA::MomentumSpaceContext& getMomentumSpaceContext() const;
 
    void generateKPlusQLookupTable();
 
    enum class EnergyType {Real, Imaginary, Complex};
 
    Algorithm getAlgorithm() const;
 
    void setEnergyType(EnergyType energyType);
 
    EnergyType getEnergyType() const;
 
    void setEnergies(
        const std::vector<std::complex<double>> &energies
    );
 
    const std::vector<std::complex<double>>& getEnergies() const;
 
    void setEnergiesAreInversionSymmetric(
        bool energiesAreInversionSymmetric
    );
 
    bool getEnergiesAreInversionSymmetric() const;
 
    void saveSusceptibilities(const std::string &filename) const;
 
    void loadSusceptibilities(const std::string &filename);
protected:
    SusceptibilityCalculator(
        Algorithm algorithm,
        const RPA::MomentumSpaceContext &momentumSpaceContext,
        int *kPlusQLookupTable/*,
        double *fermiDiracLookupTable*/
    );
 
    bool getIsMaster() const;
 
    int* getKPlusQLookupTable();
 
    const int* getKPlusQLookupTable() const;
 
    Index getSusceptibilityResultIndex(
        const Index &kIndex,
        const std::vector<int> &orbitalIndices
    ) const;
 
    const IndexedDataTree<SerializableVector<std::complex<double>>>& getSusceptibilityTree() const;
 
    template<bool useKPlusQLookupTable>
    int getKPlusQLinearIndex(
        unsigned int meshIndex,
        const std::vector<double> &k,
        int kLinearIndex
    ) const;
 
    void cacheSusceptibility(
        const std::vector<std::complex<double>> &result,
        const std::vector<double> &k,
        const std::vector<int> &orbitalIndices,
        const Index &kIndex,
        const Index &resultIndex
    );
 
    void clearCache();
private:
    IndexedDataTree<SerializableVector<std::complex<double>>> susceptibilityTree;
 
    Algorithm algorithm;
 
    EnergyType energyType;
 
    std::vector<std::complex<double>> energies;
 
    bool energiesAreInversionSymmetric;
 
    const RPA::MomentumSpaceContext *momentumSpaceContext;
 
    int *kPlusQLookupTable;
 
    bool isMaster;
};
 
inline const RPA::MomentumSpaceContext& SusceptibilityCalculator::getMomentumSpaceContext(
) const{
    return *momentumSpaceContext;
}
 
inline SusceptibilityCalculator::Algorithm SusceptibilityCalculator::getAlgorithm() const{
    return algorithm;
}
 
inline Index SusceptibilityCalculator::getSusceptibilityResultIndex(
    const Index &kIndex,
    const std::vector<int> &orbitalIndices
) const{
    return Index(
        kIndex,
        {
            orbitalIndices.at(0),
            orbitalIndices.at(1),
            orbitalIndices.at(2),
            orbitalIndices.at(3)
        }
    );
}
 
inline void SusceptibilityCalculator::setEnergyType(
    EnergyType energyType
){
    this->energyType = energyType;
}
 
inline SusceptibilityCalculator::EnergyType SusceptibilityCalculator::getEnergyType(
) const{
    return energyType;
}
 
inline void SusceptibilityCalculator::setEnergies(
    const std::vector<std::complex<double>> &energies
){
    this->energies = energies;
    susceptibilityTree.clear();
}
 
inline const std::vector<std::complex<double>>& SusceptibilityCalculator::getEnergies() const{
    return energies;
}
 
inline void SusceptibilityCalculator::setEnergiesAreInversionSymmetric(
    bool energiesAreInversionSymmetric
){
    this->energiesAreInversionSymmetric = energiesAreInversionSymmetric;
}
 
inline bool SusceptibilityCalculator::getEnergiesAreInversionSymmetric(
) const{
    return energiesAreInversionSymmetric;
}
 
inline void SusceptibilityCalculator::saveSusceptibilities(
    const std::string &filename
) const{
    Resource resource;
    resource.setData(
        susceptibilityTree.serialize(Serializable::Mode::JSON)
    );
    resource.write(filename);
}
 
inline void SusceptibilityCalculator::loadSusceptibilities(
    const std::string &filename
){
    Resource resource;
    resource.read(filename);
    susceptibilityTree = IndexedDataTree<SerializableVector<std::complex<double>>>(
        resource.getData(),
        Serializable::Mode::JSON
    );
}
 
inline std::vector<std::complex<double>> SusceptibilityCalculator::calculateSusceptibility(
        const std::vector<double> &k,
        const std::vector<int> &orbitalIndices
){
    return calculateSusceptibility(
        DualIndex(
            momentumSpaceContext->getKIndex(k),
            k
        ),
        orbitalIndices
    );
}
 
inline void SusceptibilityCalculator::clearCache(){
    susceptibilityTree.clear();
}
 
inline bool SusceptibilityCalculator::getIsMaster() const{
    return isMaster;
}
 
inline int* SusceptibilityCalculator::getKPlusQLookupTable(){
    return kPlusQLookupTable;
}
 
inline const int* SusceptibilityCalculator::getKPlusQLookupTable() const{
    return kPlusQLookupTable;
}
 
template<>
inline int SusceptibilityCalculator::getKPlusQLinearIndex<false>(
    unsigned int meshIndex,
    const std::vector<double> &k,
    int kLinearIndex
) const{
    const std::vector<std::vector<double>> &mesh
        = momentumSpaceContext->getMesh();
 
    Index kPlusQIndex
        = momentumSpaceContext->getBrillouinZone().getMinorCellIndex(
            {mesh[meshIndex][0] + k[0], mesh[meshIndex][1] + k[1]},
            momentumSpaceContext->getNumMeshPoints()
        );
    return momentumSpaceContext->getModel().getHoppingAmplitudeSet().getFirstIndexInBlock(
        kPlusQIndex
    );
}
 
template<>
inline int SusceptibilityCalculator::getKPlusQLinearIndex<true>(
    unsigned int meshIndex,
    const std::vector<double> &k,
    int kLinearIndex
) const{
    return kPlusQLookupTable[
        meshIndex*momentumSpaceContext->getMesh().size()
        + kLinearIndex/momentumSpaceContext->getNumOrbitals()
    ];
}
 
inline const IndexedDataTree<SerializableVector<std::complex<double>>>& SusceptibilityCalculator::getSusceptibilityTree() const{
    return susceptibilityTree;
}
 
};  //End of namespace TBTK
 
#endif