Theoretical study of the OH+NO₂ reaction: Formation of nitric acid and the hydroperoxyl radical

The reaction of OH with NO₂ has been studied by high level ab initio molecular orbital and statistical theory calculations. The potential energy surface for the association leading to the formation of HNO₃ by collisional deactivation and the formation of endothermic products, HO₂ and NO via the HOONO intermediate have been computed with a modified Gaussian 2 (G2M) method. The rate constants for these two channels have been calculated by means of the canonical variational RRKM approach. The predicted values correlate reasonably well with experimental data for both the forward and reverse processes.