Quasiclassical trajectory study of CH3NO2 decomposition via roaming mediated isomerization using a global potential energy surface.

We report a global potential energy surface (PES) for CH3NO2 based on fitting roughly 114,000 density functional theory (UB3LYP/6-311+g(d,p)) electronic energies. The PES is a precise, permutationally invariant fit to these energies. Properties of the PES are described, as are some preliminary quasiclassical trajectory calculations. An isomerization-roaming pathway to the CH3ONO isomer and then to the CH3O + NO products is found. Although the pathway occurs at larger distances than a related loose saddle-point on the PES, the pathway supports the supposition of such a pathway based on locating a loose first-order saddle point and associated IRC, reported previously by Zhu and Lin [Zhu, R. S. and Lin, M. C. Chem. Phys. Lett. 2009, 478, 11].