Quantum Dynamics of O(3P)+HBr→OH plus Br Reaction: Integral Cross Sections and Rate Constants and their Initial State Dependence

The integral cross sections (ICSs) and rate constants (RCs) for the title reaction are calculated by means of accurate quantum wave packet method employing the recent ab initio potential energy surface developed by Peterson and co-workers. Hundreds of partial wave contributions (up to J=150) are calculated explicitly taking Coriolis coupling into account. The ICSs are found to increase monotonically with energy and their energy dependences are smooth except in the energy range below the potential energy barrier, where several resonance peaks are observed. The temperature dependences of the RCs obey in general the Arrhenius law. These behaviors manifest the dominance of abstract mechanism. Initial rotational state (j(i)) excitations are found to greatly enhance the reactivity starting from j(i)=4, while exhibiting a complicated dependence for j(i)<4. From Boltzmann average of the initial state specified RCs (for j(i)=0-15) we obtained thermal RCs which are in reasonable agreement with available experimental results.