find_tau_from_refdet_conn Module Subroutine

    module subroutine find_tau_from_refdet_conn()

        !! Routine to find an upper bound to tau, by consideration of the
        !! singles and doubles connected to the reference determinant
        !!
        !! Obviously, this make assumptions about the possible range of pgen,
        !! so may actually give a tau that is too SMALL for the latest
        !! excitation generators, which is exciting!
        character(len=*), parameter :: this_routine = "find_tau_from_refdet_conn"

        if (tGUGA) then
            call stop_all(this_routine, "Not implemented for GUGA")
        else if (t_k_space_hubbard) then
#ifdef CMPLX_
            call stop_all(this_routine, "not implemented for complex")
#else
            call hubbard_find_tau_from_refdet_conn()
#endif
        else
            call ab_initio_find_tau_from_refdet_conn()
        end if
    end subroutine find_tau_from_refdet_conn