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 nH2O (n = 1–3) on the association energies of H2O complexes and on the barriers for the formation of O3 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 O3 formation processes: the more H2O molecules participating in the reaction, the higher stability of the association complexes and the greater the lowering of the O3 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 O3 noticeably.