Quantum real wave-packet dynamics of the N(4S) + NO (X2Π) → N2(X1Σg+) + O(3P) reaction on the ground and first excited triplet potential energy surfaces: Rate constants, cross sections and product distributions

Abstract

The reaction N + NO → N2 + O was studied by means of the time-dependent real wave-packet (WP) method and the J-shifting approximation. We consider the ground 1 3A' and first excited 13A' triplet states, which correlate with both reactants and products, using analytical PESs recently developed in our group. This work extends our previous quantum dynamics study, and probabilities, cross sections, and rate constants were calculated and interpreted on the basis of the different shapes of the PESs (barrier-less 1 3A' and with barrier 1 3A' surfaces, respectively). The WP rate constant (k1) shows a weak dependence on T (200-2500 K), as the dominant contribution to reactivity is provided by the barrier-less ground PES. There is a good agreement of WP k1 with the measurements and variational transition state theory (VTST) data, and also between the WP and VTST k1(1 3A') results. Nevertheless, there is a large discrepancy between the WP and VTST k1(1 3A') results. Product state distributions were also calculated for the much more reactive 1 3A' PES. There is an excellent agreement with the experimental average fraction of vibrational energy in N2 (25±3 %), the only measured dynamics property of this reaction.