A new ab initio based global HOOH(13A") potential energy surface for the O(3P) + H2O(X1A1) ⇆ OH(X2Π) + OH(X2Π) reaction

An accurate global potential energy surface is developed for the title reaction by fitting more than 36 000 of ab initio points at the CCSD(T)/AVTZ level using the permutation invariant polynomial method. The canonical rate constants for both the forward and reverse directions of the title reaction are determined on the new potential energy surface and the agreement with experiment is satisfactory. In addition, the dynamics of the forward reaction is investigated with the quasi-classical trajectory method. It is found that this direct abstraction reaction has a backward bias in its product angular distribution, consistent with a direct rebound mechanism. The OH product newly formed by the reaction exhibits a bimodal rotational state distribution, due apparently to secondary collisions with the slowly recoiling spectator OH product. (C) 2013 AIP Publishing LLC.