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

Wave packet calculations, using direct and damped-L-2 real propagation meth ods, of initial state-resolved and cumulative reaction probabilities for th e O(P-3)+HCl((1)Sigma(+))--> OH((2)Pi)+Cl(P-2) reaction are reported. Resul ts are obtained using the recently developed "S4" potential surface of Rama chandran and co-workers and, for comparison, the earlier Koizumi, Schatz, a nd Gordon (KSG) potential energy surface. Most calculations are for total a ngular momentum J=0, although some J > 0 centrifugal sudden results are als o obtained. The thermal rate constant and the rate constant for HCl(v=1) ar e obtained from the J=0 cumulative reaction probability and J-K-shifting, u sing standard transition-state rotation constants. This type of shifting is justified by examining limited centrifugal sudden calculations. The S4 sur face is shown to yield some surprising results. For example, despite a sign ificantly higher ground state adiabatic barrier than the KSG surface, the t hermal 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].