calc_nsites_aim_star Function

    function calc_nsites_aim_star(this, length_x, length_y, length_z) result(n_sites)
        ! for the star geometry with maybe
        class(aim_star) :: this
        integer, intent(in) :: length_x, length_y
        integer, intent(in), optional :: length_z
        integer :: n_sites
        character(*), parameter :: this_routine = "calc_nsites_aim_star"

        unused_var(this)
        if (present(length_z)) then
            unused_var(length_z)
        end if

        if (length_x < 1) then
            call stop_all(this_routine, "n_imps < 1!")
        end if
        if (length_y < 1) then
            call stop_all(this_routine, "n_bath < 1!")
        end if

        n_sites = length_x + length_y

    end function calc_nsites_aim_star