An improved potential energy surface for the C + NO reaction

Abstract

A new potential energy surface for the reaction between C(³P) and NO(X²Π) is presented. The surface is based on 998 ab initio energy points, of which 578 are new points calculated in this work. Complete active space second-order perturbation theory has been employed using a (14s9p4d3f)/[4s3p2d1f] contracted ANO basis. An analytic fit of the ²A″ surface is presented with special attention paid to the long-range part of the potential. This surface improves a previously published surface (Simonson et al., Chem. Phys., 1995, 200, 141), which was based on more limited ab initio data. In particular the long-range part of the potential and non-linear geometries have been improved, including the description of several stationary points. Thermal rate coefficients for formation of CN(X²Σ ⁺ ) + O(³P) and CO(X¹Σ ⁺ ) + N(²D) in the temperature range from 200 K to 4500 K have been obtained using quasiclassical trajectory calculations. While the total rate constant agrees better with experiment for the new surface, the branching ratio appears to agree better on the old surface, which is discussed.