Authors: Qingyong Meng Hua Dong MingBao Huang
Publish Date: 2012/03/02
Volume: 131, Issue: 3, Pages: 1194-
Abstract
For studying the adiabatic and nonadiabatic mechanisms of the ClO X 2Π + ClO X 2Π → ClOOCl → 2Cl 2 P u + O2 X 3Σ g − reaction 1 and the ClO X 2Π + ClO X 2Π → ClOOCl → Cl2 X 1Σ g + + O2 X 3Σ g − reaction 2 we calculated by partial geometry optimizations under the C2 constraint the O–O and O–Cl dissociation potential energy curves PECs from the five lowlying states of ClOOCl at the CASPT2 level The CASSCF minimumenergy crossing point MECP between the potential energy surfaces of the 1 1A ground state correlating with the product of reaction 1 and the 1 3B state correlating with the product of reaction 2 states was also determined Based on the CAS calculation results PECs energies and spin–orbit coupling at the MECP we predict that reaction 1 occurs along pathway 1 ClO X 2Π + ClO X 2Π → ClOOCl 1 1A → 2Cl 2 P u + O2 X 3Σ g − and that reaction 2 occurs along pathway 2 ClO X 2Π + ClO X 2Π → ClOOCl 1 1A → 1 1A/1 3B MECP 1424 cm−1 → ClOOCl 1 3B → Cl2 X 1Σ g + + O2 X 3Σ g − The needed energies relative to the reactant for pathways 1 and 2 are predicted to be 53 and 111 kcal/mol respectively which indicates that reaction 1 is more favorable than reaction 2 The present work supports the traditional photochemical model for ozone degradation ClOOCl 1 1A formed by two ClO X 2Π can directly produce O2 plus two Cl atoms
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