get_diagonal_matel Function

    function get_diagonal_matel(nI, ilut) result(diagH)
        ! Get the diagonal element for a determinant nI with ilut representation ilut

        ! In:  nI        - The determinant to evaluate
        !      ilut      - Bit representation (only used with HPHF)
        ! Ret: diagH     - The diagonal matrix element
        integer, intent(in) :: nI(nel)
        integer(n_int), intent(in) :: ilut(0:NIfTot)
#ifdef CMPLX_
        debug_function_name("get_diagonal_matel")
#endif
        real(dp) :: diagH

        if (tHPHF) then
            associate(h_el => hphf_diag_helement(nI, ilut))
#ifdef CMPLX_
                ASSERT(near_zero(aimag(h_el)))
#endif
                diagH = real(h_el, dp)
            end associate
        else
            associate(h_el => get_helement(nI, nI, 0))
#ifdef CMPLX_
                ASSERT(near_zero(aimag(h_el)))
#endif
                diagH = real(h_el, dp)
            end associate
        end if

    end function get_diagonal_matel