EFP2.h

#ifndef EFP2_H_INCLUDED
#define EFP2_H_INCLUDED

#include <vector>

class EFP2_impl;
class InputSection;

class EFP2 {
public:
	/* Initialize EFP2 instance using user's input. */
	void init(InputSection &);

	/* Returns true if the current EFP2 instance was initialized. */
	bool initialized();

    /* Returns if_multipole_field value. */
    bool get_if_multipole_field();

    /* Returns updated if_multipole_field value. */
    void update_multipole_field();

    /* Returns if_pol_field value. */
    bool get_if_pol_field();

    /* Returns updated if_pol_field value. */
    void update_pol_field();

	/* Reorient EFP fragments according to Q-Chem's orientation of
	 * ab initio subsystem. */
	void reorient_geometry();

	/* Print geometry of EFP subsystem. */
	void print_geometry();

	/* Setup all necessary stuff for AI/EFP dispersion computation
	 * if enabled */
	void setup_aiefp_dispersion();

	/* Compute all EFP and the rest of QM/EFP interactions after
	 * the QM SCF has converged.
	 * \p do_grad - specifies whether to compute the gradient.
	 * If \p do_grad is not zero than the gradient will also be
	 * computed. */
	void compute(int do_grad);

    /* Update quantum mechanical Hamiltonian with the contributions
 * from EFP multipoles and atoms using AOints.
 * \p h - a Hamiltonian matrix.
 * \p code - Q-Chem's ShlPrs code. */
    void update_mult_ints(double *h, INTEGER code);

    /* Update quantum mechanical Hamiltonian with the contributions
 * from EFP induced diples using AOints.
 * \p h - a Hamiltonian matrix.
 * \p code - Q-Chem's ShlPrs code. */
    void update_pol_ints(double *h, INTEGER code);

    /* Update quantum mechanical Hamiltonian with the contributions
	 * from EFPs using AOints.
	 * \p h - a Hamiltonian matrix.
	 * \p code - Q-Chem's ShlPrs code. */
	// void update_wf(double *h, INTEGER code);

	/* Update quantum mechanical Hamiltonian with the contributions
	 * from EFPs using libqints.
	 * \p h - a Hamiltonian matrix.
	 * \p code - Q-Chem's ShlPrs code. */
	void update_wf_qints(double *h, INTEGER code);

	/* Update the positions of quantum nuclei for libefp. */
	void update_qm_atoms();

	/* Returns the wavefunction dependent energy.
	 * \p w - is a density matrix.
	 * \p n - is a total number of elements in array \p w. */
	double get_wf_dependent_energy(double *w, double n);

	/* Returns the total EFP energy. */
	double get_total_energy();

	/* Returns EFP correction to the energy of the excited state.
	 * \p w - is the density matrix of the excited state WF.
	 * \p n - is the total number of elements in array \p w.
	 * \p Ecis - excitation energy */
	double get_excited_state_energy_correction(double *w, size_t n, double Ecis);

    /* Returns gradient on quantum nuclei from EFP electrostatics.
	 * Upon return the \p a vector will contain 3*N elements of
	 * gradient, where N is the number of QM atoms. */
	void get_qm_gradient(std::vector<double> &a);

	/* Returns current EFP gradient.
	 * The vector \p a will contain 6*N gradient values for
	 * fragment translation and rotation. N is the total number of
	 * EFP fragments. */
	void get_gradient(std::vector<double> &a);

    /* computes pairwise energies between QM region and EFP fragments.
     *  \p Escf - reference AI energy (HF or excitation energy)
     *  \p if_excited = 1/0 a switch to distinguish between the ground state (0) or excited state (1). */
    void get_pairwise_energy(double Estate, int if_excited);

	/* Print EFP energy terms to stdout. */
	void print_energy();

    /* Print pairwise energy decomposition to stdout.
     * \p if_excited = 1/0 a switch to distinguish between the ground state (0) or excited state (1). */
    void print_pairwise_energy(int if_excited);

    /* Returns a EFP2 singleton instance. */
	static EFP2& instance() {
		static EFP2 instance;
		return instance;
	}

private:
	EFP2();
	EFP2(const EFP2 &);
	~EFP2();

	EFP2_impl *impl_;
};

#endif /* EFP2_H_INCLUDED */