On the mechanism of HOONO to HONO2 conversion.

We have conducted an examination (using density functional theory) of possible transition states that could lead to HNO3 from peroxynitrous acid (HOONO) and one or two water molecules. We find no transition states with free energies in the range of 20 kcal/mol, i.e., near the experimental value in solution. The implications for the mechanism of conversion of HOONO to nitrate are discussed.