Quantum real wave-packet dynamics of the N(4S)+NO((X)over-tilde 2Π)→N2((X)over-tilde 1Σg+)+O(3P) reaction on the ground and first excited triplet potential energy surfaces:: Rate constants, cross sections, and product distributions

The reaction N+NO -> N-2+O was studied by means of the time-dependent real wave-packet (WP) method and the J-shifting approximation. We consider the ground 1 (3)A '' and first excited 1 (3)A' triplet states, which correlate with both reactants and products, using analytical potential energy surfaces (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 (barrierless 1 (3)A '' and with barrier 1 (3)A' surfaces, respectively). The WP rate constant (k(1)) shows a weak dependence on T(200-2500 K), as the dominant contribution to reactivity is provided by the barrierless ground PES. There is a good agreement of WP k(1) with the measurements and variational transition state theory (VTST) data, and also between the WP and VTST k(1)(1 (3)A '') results. Nevertheless, there is a large discrepancy between the WP and VTST k(1)(1 (3)A') results. Product state distributions were also calculated for the much more reactive 1 (3)A '' PES. There is an excellent agreement with the experimental average fraction of vibrational energy in N-2(25 +/- 3%), the only measured dynamics property of this reaction. (c) 2006 American Institute of Physics.