Complete active space second order perturbation theory (CASPT2) study of N(2D) + H2O reaction paths on D1 and D0 potential energy surfaces: Direct and roaming pathways

We report reaction paths starting from N(D-2) + H2O for doublet spin states, D-0 and D-1. The potential energy surfaces are explored in an automated fashion using the global reaction route mapping strategy. The critical points and reaction paths have been fully optimized at the complete active space second order perturbation theory level taking all valence electrons in the active space. In addition to direct dissociation pathways that would be dominant, three roaming processes, two roaming dissociation, and one roaming isomerization: (1) H2ON -> H-O(H)N -> H-HON -> NO((2)Pi) + H-2, (2) cis-HNOH. HNO-H -> H-HNO -> NO + H-2, (3) H2NO -> H-HNO -> HNO-H -> trans-HNOH, are confirmed on the D-0 surface. (C) 2014 AIP Publishing LLC.