Competition between dissociation and exchange processes in a collinear A + BC collision. I. Exact quantum results

Exact quantum results for collision-induced dissociation on a reactive surface are presented. A modified LEPS potential-energy surface modeling the H + HD → H₂ + D system has been used. HD and H₂ bearing respectively 7 and 6 bound states. This system has been chosen because it displays significant reactive scattering for total energies above the dissociation threshold. Calculations have been performed using the time-dependent wavepacket method for two initial vibrational quantum numbers of the HD molecule (v = 0, 2). For each vibrational quantum number, two wavepackets with overlapping energy distributions have been run, covering a total energy range up to more than three times the dissociation energy. Comparison with previous collision-induced dissociation calculations shows that the dissociation is greatly enhanced by the presence of concomitant reactive scattering. A vibrational enhancement effect is also observed above the dissociation threshold; for higher energies the system exhibits a pronounced vibrational inhibition effect.