Ab initio and DFT study of the ground 3A′ potential energy surface for the O(3P)+N2O→2NO reaction

An ab initio CASPT2//CASSCF and a DFT B3LYP study of the ground 3A′ potential energy surface (PES) for the title reaction have been carried out. Two reaction paths with cis- and trans- arrangements are described. Surface crossings are noted in both paths, while bifurcative behaviour is present in the energetically favoured cis-path. These phenomena have been analysed in more detail at the DFT level. The rate constant values have been calculated by means of the conventional transition state theory, including the contribution from the ground 3A″ PES (reported elsewhere), yielding very good accordance with the experiment in the case of the CASPT2//CASSCF method.