ON THE FRAGMENTATION DYNAMICS OF NH3-]NH2-ENERGY SURFACES(H .1. MRD CI POTENTIAL)

To provide a potential energy surface (PES) for a three-dimensional vi brational model of the dissociation dynamics of ammonia in the (A) ove r tilde state, accurate MRD-CI computations were carried out for a wid e range of displacements in the out-of-plane and in-plane bending coor dinates along the H-NH2 dissociation coordinate. Some characteristic f eatures of the (A) over tilde-state PES, such as the height and positi on of the barrier to dissociation and the dependence of the PES On the out-of-plane angle, differ noticeably from earlier work on this syste m. The values for the height of the barrier computed from the MRD-CI e xtrapolation, full CI, and secular equation estimates are 0.38, 0.34, and 0.32 eV, respectively. (C) 1996 John Wiley & Sons.