H2O-catalyzed formation of O3 in the self-reaction of HO2:: a computational study on the effect of nH2O (n=1-3)

The effect of nH(2)O (n = 1-3) on the association energies of H2O complexes and on the barriers for the formation of O-3 in the self-reaction of HO2 reaction has been investigated by ab initio molecular orbital calculations at the modified Gaussian-2 (G2M) level of theory. The results show that H2O can affect the complex and O-3 formation processes: the more H2O molecules participating in the reaction, the higher stability of the association complexes and the greater the lowering of the O-3 elimination barrier becomes. For the isomers of the reactions, more hydrogen bonds being formed in the complexes enhances their stabilities. A preliminary kinetic calculation shows that below room temperature, H2O may enhance the formation of O-3 noticeably.