KetPair.hpp

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// SPDX-FileCopyrightText: 2024 Pairinteraction Developers
// SPDX-License-Identifier: LGPL-3.0-or-later
 
#pragma once
 
#include "pairinteraction/ket/Ket.hpp"
#include "pairinteraction/utils/traits.hpp"
 
#include <complex>
#include <initializer_list>
#include <memory>
#include <string>
#include <type_traits>
#include <vector>
 
namespace pairinteraction {
template <typename Scalar>
class BasisPairCreator;
 
template <typename Scalar>
class BasisAtom;
 
template <typename Scalar>
class KetPair : public Ket {
    static_assert(traits::NumTraits<Scalar>::from_floating_point_v);
 
    using real_t = typename traits::NumTraits<Scalar>::real_t;
 
    friend class BasisPairCreator<Scalar>;
    struct Private {};
 
public:
    KetPair(Private /*unused*/, std::initializer_list<size_t> atomic_indices,
            std::initializer_list<std::shared_ptr<const BasisAtom<Scalar>>> atomic_bases,
            real_t energy);
 
    std::string get_label() const override;
    std::shared_ptr<KetPair<Scalar>>
    get_ket_for_different_quantum_number_m(real_t new_quantum_number_m) const;
    std::vector<std::shared_ptr<const BasisAtom<Scalar>>> get_atomic_states() const;
 
    bool operator==(const KetPair<Scalar> &other) const;
    bool operator!=(const KetPair<Scalar> &other) const;
 
    struct hash {
        std::size_t operator()(const KetPair<Scalar> &k) const;
    };
 
private:
    std::vector<size_t> atomic_indices;
    std::vector<std::shared_ptr<const BasisAtom<Scalar>>> atomic_bases;
    static real_t
    calculate_quantum_number_f(const std::vector<size_t> &indices,
                               const std::vector<std::shared_ptr<const BasisAtom<Scalar>>> &bases);
    static real_t
    calculate_quantum_number_m(const std::vector<size_t> &indices,
                               const std::vector<std::shared_ptr<const BasisAtom<Scalar>>> &bases);
    static Parity
    calculate_parity(const std::vector<size_t> &indices,
                     const std::vector<std::shared_ptr<const BasisAtom<Scalar>>> &bases);
};
 
extern template class KetPair<double>;
extern template class KetPair<std::complex<double>>;
} // namespace pairinteraction