A CASPT2 study of the doublet potential energy surface for the CH(X2Π)+N2(X1Σ+g) reaction

The HCN2 --> H + NCN((3)Sigma(g)(-)) reaction, which is a key process in the CH((2)Pi) + N-2 reaction mechanisms, has been studied using the ab initio electronic structure method at the CASPT2 level theory. First, we calculated two-dimensional potential energy surfaces as a function of two appropriate coordinates in order to understand overall mechanisms. Then, full-dimensional stationary point searches have been carried out using locally interpolated potential energy surfaces. Our calculations strongly support the recent proposal of Lin and co-workers that the CH((2)Pi) + N2 reaction does not yield spin-forbidden N(S-4) + HCN products but yield spin-allowed H (S-2) + NCN((3)Sigma(g)(-)) products. (C) 2002 Published by Elsevier Science B.V.