is_in_ref_spatial Function

    logical function is_in_ref_spatial(orb, part_type)
        ! the same function as above, but for a spatial orbital orb
        integer, intent(in) :: orb
        integer, intent(in), optional :: part_type
        character(*), parameter :: this_routine = "is_in_ref_spatial"

        integer :: temp_part_type
        integer(n_int) :: temp_ilut(0:niftot)

        ASSERT(orb >= 0)
        ASSERT(orb <= nBasis / 2)

        if (present(part_type)) then
            temp_part_type = part_type
        else
            temp_part_type = 1
        end if

        ! there is an inefficient way to check projedet:

        temp_ilut = ilutref(:, part_type_to_run(temp_part_type))
        is_in_ref_spatial = (IsOcc(temp_ilut, 2 * orb) .or. IsOcc(temp_ilut, 2 * orb - 1))

    end function is_in_ref_spatial