The reaction of F with N 3 studied using multiconfiguration wave functions

Abstract

CASSCF (complete active space self-consistent field) and CASPT2 (multiconfiguration second-order perturbation theory) calculations with the cc-pVTZ and cc-pVQZ basis sets were carried out for exploring the mechanisms of the N 3 + F → NF( 1 Δ ) + N 2 (i) and N 3 + F → NF( 3 Σ − ) + N 2 (ii) reactions. The CASSCF and CASPT2 calculations indicate that channel (i) occurs in the 1 A ′ potential energy surface (PES) and along the reaction path there exists an intermediate [IM ( 1 A ′ )] followed by a transition state and that channel (i) is energetically feasible. The CASSCF calculations indicate that channel (ii) occurs in the 3 A″ PES and it has a single step with a transition state [TS( 3 A″ )], but the CASPT2 single-point calculations imply that TS( 3 A″ ) may not exist. The 1 A ′ and 3 A″ PES crossing was explored by performing conical intersection and spin–orbit coupling calculations at the CASSCF level and the calculations imply that the crossing may not cause predissociation of IM( 1 A ′ ) into the triplet ground state product.