material.h

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#ifndef PSIM_MATERIAL_H
#define PSIM_MATERIAL_H
 
#include "phonon.h"// for Phonon, Phonon::RelaxRates, Phonon::Polariz...
#include <array>// for array
#include <cstddef>// for size_t
#include <utility>// for pair, move
#include <vector>// for vector
 
struct DispersionData;
struct RelaxationData;
struct TableData;
 
 
class Material {
public:
    static constexpr std::size_t NUM_FREQ_BINS = 1000;// Used on one occasion outside this class
 
    using Array = std::array<double, NUM_FREQ_BINS>;
    using Table = std::array<std::pair<double, double>, NUM_FREQ_BINS>;
    using Polar = Phonon::Polarization;
 
    Material(std::size_t mat_id, const DispersionData& disp_data, const RelaxationData& relax_data);
 
    void setFullSimulation() noexcept {
        full_simulation_ = true;
    }
 
    [[nodiscard]] std::size_t id() const noexcept {
        return id_;
    }
    [[nodiscard]] double max_freq_la() const noexcept {
        return w_max_la_;
    }
    [[nodiscard]] double max_freq_ta() const noexcept {
        return w_max_ta_;
    }
    [[nodiscard]] Phonon::RelaxRates relaxRates(double temp, double freq, Polar polarization) const noexcept;
    [[nodiscard]] Phonon::RelaxRates relaxRates(std::size_t freq_index, Polar polarization, double temp) const;
    [[nodiscard]] static std::pair<std::size_t, Polar> freqIndex(const Table& dist) noexcept;
 
    [[nodiscard]] const Array& getFrequencies() const noexcept {
        return frequencies_;
    }
    [[nodiscard]] double getFreq(std::size_t index) const noexcept;
    [[nodiscard]] double getVel(std::size_t index, Polar polar) const noexcept;
    [[nodiscard]] const Table* baseTable(double temp) const {
        return baseData(temp).first;
    }
    [[nodiscard]] double baseEnergy(double temp) const {
        return baseData(temp).second;
    }
    [[nodiscard]] const Table* emitTable(double temp) const {
        return emitData(temp).first;
    }
    // Needed to determine the amount of energy emitted by emitting surfaces
    [[nodiscard]] double emitEnergy(double temp) const {
        return emitData(temp).second;
    }
    [[nodiscard]] const Table* scatterTable(double temp) const {
        return scatterData(temp).first;
    }
    // Needed for second numerical inversion when doing a full simulation
    [[nodiscard]] double scatterEnergy(double temp) const {
        return scatterData(temp).second;
    }
    // If pseudo=true -> scales results by the relaxation rates (returns scatterEnergy(temp))
    [[nodiscard]] double theoreticalEnergy(double temp, bool pseudo = false) const noexcept;
    void initializeTables(double low_temp, double high_temp, float temp_interval);
 
private:
    std::size_t id_;
    double b_l_;
    double b_tn_;
    double b_tu_;
    double b_i_;
    double w_;// Cutoff for TA Umklapp scattering
 
    double w_max_la_;// Maximum frequency of LA phonons that can exist in this material
    double w_max_ta_;
 
    double freq_width_;// Width of frequency bin.
    bool full_simulation_{ false };
 
    Array frequencies_{ 0. };
    Array densities_la_{ 0. };
    Array densities_ta_{ 0. };
    Array velocities_la_{ 0. };
    Array velocities_ta_{ 0. };
 
    std::vector<double> temps_;
    std::vector<TableData> base_tables_;
    std::vector<TableData> emit_tables_;
    std::vector<TableData> scatter_tables_;
 
    [[nodiscard]] static double getK(double freq, std::array<double, 3> coeffs);
    [[nodiscard]] static double getGv(double freq, std::array<double, 3> coeffs);
 
    [[nodiscard]] std::pair<const Table*, double> baseData(double temp) const;
    [[nodiscard]] std::pair<const Table*, double> emitData(double temp) const;
    [[nodiscard]] std::pair<const Table*, double> scatterData(double temp) const;
 
    [[nodiscard]] std::pair<Table, double> cumulDistEmit(Array&& la_dist, Array&& ta_dist) const;
    [[nodiscard]] std::pair<Table, double> cumulDistScatter(Array&& la_dist, Array&& ta_dist, double temp) const;
    [[nodiscard]] static Table buildCumulDist(const Array& t1, const Array& t2);// NOLINT
    [[nodiscard]] Array phononDist(double temp, Polar polarization) const;
 
    [[nodiscard]] double tauNInv(double temp, double freq, Polar polarization) const noexcept;
    [[nodiscard]] double tauUInv(double temp, double freq, Polar polarization) const noexcept;
    [[nodiscard]] double tauIInv(double freq) const noexcept;// Impurity scattering
 
    static void verifyInput(double low_temp, double high_temp, float interval_size);
    [[nodiscard]] std::size_t getTempIndex(double temp) const noexcept;
};
 
// Should extend this to a class
struct RelaxationData {
    double b_l{ 0. };
    double b_tn{ 0. };
    double b_tu{ 0. };
    double b_i{ 0. };
    double w{ 0. };
};
 
// Only handles quadratic data - consider extending to a class as well
struct DispersionData {
    std::array<double, 3> LA_data{
        0.,
        0.,
        0.,
    };
    std::array<double, 3> TA_data{
        0.,
        0.,
        0.,
    };
    // std::Array<double, 3> LO_data {0., 0., 0.,};
    // std::Array<double, 3> TO_data {0., 0., 0.,};
    double w_max_la{ 0. };
    double w_max_ta{ 0. };
};
 
struct TableData {
    TableData(Material::Table mat_table, double cumulative_sum)
        : table{ std::move(mat_table) }
        , cumul_sum{ cumulative_sum } {
    }
 
    std::array<std::pair<double, double>, Material::NUM_FREQ_BINS> table;
    double cumul_sum{ 0. };
};
 
#endif// PSIM_MATERIAL_H