NON-BORN-OPPENHEIMER CORRECTION TO THE H-3-DATA( POTENTIAL FROM EXPERIMENTAL)

The spectrum of D3+ is analyzed using a spectroscopically determined e ffective H-3+ Potential [B. M. Dinelli, S. Miller, and J. Tennyson, J. Mol. Spectrosc. 163, 71 (1994)] and an accurate ab initio potential [ G. C. Lie and D. Frye, J. Chem. Phys. 96, 6784 (1992)]. Calculations s uggest that the major error in the potential of Lie and Frye is due to the Born-Oppenheimer approximation. D3+ spectroscopic data are used t o construct both Born-Oppenheimer and mass-dependent adiabatic surface s for the H-3+ system by fitting only one parameter. These surfaces re produce the fundamental rovibrational transitions of H-3+ and D3+ to w ithin 0.03 cm-1. An accurate adiabatic surface has not previously been determined for a polyatomic molecule.