A comparative study of the quantum dynamics and rate constants of the O(3P)+HCl reaction described by two potential surfaces

Wave packet calculations, using direct and damped-L-2 real propagation methods, of initial state-resolved and cumulative reaction probabilities for the O(P-3)+HCl((1)Sigma(+))--> OH((2)Pi)+Cl(P-2) reaction are reported. Results are obtained using the recently developed S4 potential surface of Ramachandran and co-workers and, for comparison, the earlier Koizumi, Schatz, and Gordon (KSG) potential energy surface. Most calculations are for total angular momentum J=0, although some J > 0 centrifugal sudden results are also obtained. The thermal rate constant and the rate constant for HCl(v=1) are obtained from the J=0 cumulative reaction probability and J-K-shifting, using standard transition-state rotation constants. This type of shifting is justified by examining limited centrifugal sudden calculations. The S4 surface is shown to yield some surprising results. For example, despite a significantly higher ground state adiabatic barrier than the KSG surface, the thermal rate constant is not significantly different from one obtained with the KSG surface, although the one for the vibrationally excited HCl is. (C) 2000 American Institute of Physics. [S0021- 9606(00)30824-8].