ACCURATE QUANTUM DYNAMICS OF THE LIGHT ATOM-TRANSFER CHEMICAL-REACTION O+HCL-]OH+CL

The hydrogen atom transfer reaction between two heavy atoms, O(P-3)+HCl(upsilon(i)=0j(i)=0-2)-->OH(upsilon(f)=0,1j(f))+Cl, is studied quantum mechanically accurately with use of the hyperspherical coordinate approach, where upsilon(lambda) and j(lambda) designate the vibrational and rotational quantum numbers in the lambda arrangement channel. The collision energy considered in this study ranges up to similar to 0.7 eV, and the total angular momentum J is required up to similar to 120. The potential energy surface employed is the one derived by Koizumi, Schatz, and Gordon (KSG) based on ab initio data. The effects of the potential energy surface topography on the dynamics are analyzed in terms of the collision energy dependence and the j(i) dependence. The effects of the nonlinearity of the transition state of the KSG surface is clearly manifested in these dynamics. Not only the accurate integral cross section and the rate constant are evaluated, but also the Omega(i) dependence of the dynamics and final rotational state distribution are analyzed, where Omega(i) is the z-component of J in the initial arrangement channel. The j(f) distribution at E(coll)greater than or equal to 0.5 eV shows an interesting resemblance with the feature recently observed experimentally. The energy-shift approximation is extended so as to cover the general triatomic systems which require a large number of J. This extended CCPA (constant centrifugal potential approximation) is shown to work well.