Research on the model reactions of ClONO2 with HCl on water clusters

The reaction of ClONO2 with HCl on ice or on PSC surfaces occurs readily. However, the rate of ClONO2 reacting with HCl in pure gas phase is small. In order to understand the reaction conditions of ClONO2 with HCl, several model reactions of ClONO2 with the (H2O)n·HCl clusters for n=0,1,2,3,4 have been theoretically studied at the MP2//HF/6-31G(d) level and for n=0,1 at the MP2/6-31G(d) level. One of the reactions for n=3 has been further calculated at the MP2//HF/6-31G(d,p), MP2//HF/6-311G(d,p), and MP2//HF/6-311+G(d,p) levels. Numerical results show that the reaction of ClONO2 with HCl on a three- or four-water cluster proceeds faster with a low-energy barrier. The implication for ozone holes in the Antartic and Artic stratosphere is discussed.