is_allowed_ueg_k_vector Function

    function is_allowed_ueg_k_vector(orbi, orbj, orba) result(is_allowed)
        integer, intent(in) :: orbi, orbj, orba
        logical :: is_allowed

        integer :: ki(3), kj(3), ka(3), kb(3)
        real(dp) :: testE

        ki = G1(orbi)%k
        kj = G1(orbj)%k

        ! Obtain the new momentum vectors
        ka = G1(orba)%k
        kb = ki + kj - ka

        ! Is kb allowed by the size of the space?
        testE = sum(kb**2)
        if (abs(kb(1)) <= nmaxx .and. abs(kb(2)) <= nmaxy .and. &
            abs(kb(3)) <= nmaxz .and. &
            (.not. (tOrbECutoff .and. (testE > OrbECutoff)))) then

            is_allowed = .true.
        else
            is_allowed = .false.
        end if

    end function is_allowed_ueg_k_vector