EFFECTIVE ROTATION PSEUDOROTATION HAMILTONIAN FOR X(3)-TYPE MOLECULESIN THE HIGH-BARRIER LIMIT

The rotation-pseudorotation problem in X(3)-type molecules has been tr eated group-theoretically for the high-barrier tunneling case. Explici t expressions for rotation-pseudorotation Hamiltonian matrix elements, which take into account the interaction of overall rotation with the rotation of principal axes accompanying pseudorotation motion and with the angular momentum generated by pseudorotation motion, have been de rived using an m-fold extended group of the G(12) permutation-inversio n group. Illustrative pseudorotation tunneling splitting patterns have been derived by numerically diagonalizing the resulting Hamiltonian m atrix for J = 5, using rotational constants appropriate for Na-3 in th e B state, together with various sets of tunneling parameters. These t unneling splittings can be qualitatively understood using the concept of twofold energy level clusters in asymmetric rotor molecules. (C) 19 95 Academic Press, Inc.