A CASPT2 study of the doublet potential energy surface for the CH(X2Π)+N2(X1Σg+) reaction

The HCN2→H+NCN(3Σg−) reaction, which is a key process in the CH(2Π)+N2 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(2Π)+N2 reaction does not yield spin-forbidden N(4S)+HCN products but yield spin-allowed H(2S)+NCN(3Σg−) products.