			15min:

ROTATIONAL AND ROVIBRATIONAL CONSTANTS FOR TRIATOMIC MOLECULES FROM FOURTH-ORDER PERTURBATION THEORY.

DEVIN A. MATTHEWS, JUSTIN Z. GONG AND JOHN F. STANTON, Department of Chemistry and Biochemistry, Institute for Theoretical Chemistry, The University of Texas at Austin, Austin, Texas 78712.

Rotational and rovibrational constants including the quadratic vibration-rotation interaction constants (the `` gamma "s), vibrationally-dependent quartic centrifugal distortion constants, and equilibrium hexic centrifugal distortion constants for general non-linear triatomic molecules as derived from fourth-order Rayleigh-Schrödinger perturbation theory (VPT4) are presented. The derived constants include all terms from the Watson Hamiltonian except for the pseudopotential. The resulting expressions are applied to a model molecular system, and issues such as vibrational resonance are discussed.