The OH initiated oxidation of nitric oxide (NO) is an important atmospheric
reaction being, during the day time, the main channel that leads to the formation of
HONO a reservoir species for both OH and odd nitrogen. This work reports ab initio study
of the Potential Energy Surface (PES) of NO + OH using density functional theory
calculations conducted at the B3LYP level of theory with a 6-311g (d,p) basis set. We
confirmed experimental observations pointing out that the main channel for this reaction
is the formation the HONO. From the addition of OH to NO both cis and trans isomers of
HONO were found to be the formed as stable intermediate, both having a negative
enthalpy of formation relative to the reactants, the cis isomer being more stable than the
trans one. The ab initio calculations were extended to include the hydrogen extraction
mechanism with its respective transition state to investigate the potential existence of a
reaction channel leading to the formation of NO2 + H, that was found not to be of
significant interest.
