New analytical (2A′,4A′) surfaces and theoretical rate constants for the N(4S)+O2 reaction

Abstract

We report two new analytical fits of the ground potential energy surface ͑PES͒ ( 2 AЈ) and the first excited PES ( 4 AЈ) involved into the title reaction and its reverse, using ab initio electronic structure calculations from Papers I and II along with new grids of ab initio points by means of the second-order perturbation theory on CASSCF wave function ͓CASPT2 ͑17,12͒ G2/aug-cc-pVTZ͔ reported here ͑1250 points for the 2 AЈ PES and 910 points for the 4 AЈ PES͒. Some experimental data were also introduced to better account for the exoergicity and the experimental rate constant at 300 K. The final root-mean-square deviations of the fits were 1.06 and 1.67 kcal/mol for 2 AЈ and the 4 AЈ PESs, respectively, for the NOO C s abstraction and insertion regions of the PESs. Thermal rate constants were calculated ͑300-5000 K͒ for both the direct and reverse reactions by means of the variational transition state theory with the inclusion of a microcanonical optimized multidimensional tunneling correction, obtaining a very good agreement with the experimental data within all the temperature range. The new analytical 2 AЈ PES presents several stationary points not introduced in previous analytical surfaces, and describes accurately the NO 2 (X 2 A 1 ) minimum, which seems to be very accessible according to the trajectories run in a preliminary quasiclassical trajectory study. The new analytical 4 AЈ PES has a lower energy barrier than the previous one, which increases significantly the contribution of this PES to the total rate constant at high temperatures. Moreover, the new analytical PESs not only describe accurately the C s regions of the NOO system but also the ONO C 2v or near C 2v regions.

N2, O2, NO state-to-state vibrational kinetics in hypersonic boundary layers: The problem of rescaling rate coefficients to uniform vibrational ladders

“…These two PESs have been accurately calculated by the same group of Barcelona University [31,32] who calculated the two PESs of reaction (10.b), so the analytical expression of these 2 A 0 and 4 A 0 PESs [33] is chosen in the present study. The rates of reaction (11) are obtained by a weighted sum in the following way:…”

Quasiclassical trajectory study of the rotational distribution for the O+NO(v = 0) fundamental vibrational excitation

“…Tentatively, one could think of rationalizing the above differences from the results of Sharma and Duff [8] by correlating the final rotational temperature with the NO 2 well depth, since deep minima are expected to enhance randomization of the various degrees of freedom and eventually lead to formation of thermalized products. In fact, the MBE PES of Sayós et al [13] for the A state has a potential well slightly deeper than the DMBE one, which could conceivably explain the fact of the associated rotational distribution at T = 750 K lying closer to 750 K than the DMBE prediction itself. Thus, one could to some extent attribute the differences between our prediction and the one of Sharma and Duff [8] to the shallower minima of the LEPS forms.…”

“…For example Sayós et al have reported a series of studies [13,14] for different states of the NO 2 system, focusing mainly on the study of N + O 2 collision, whereas Ivanov et al [15] studied exchange and recombination on the O( 3 P ) + NO( 2 ) reaction with a newly fitted potential function. Although there is a vast literature on the NO 2 system (a complete review is out of the scope of this work), the specificity of the energy transfer of the title transition makes it a subject not so extensively explored.…”

Physics and chemistry of the influence of excited molecules on combustion enhancement

“…The rate constant of reaction (3.33) was established with rather high accuracy, and measurements of different researchers are in good consistency with each other [62]. this reaction, conducted in [63,64], it was established that the activation barrier of reaction (3.33) was about 3000 K.…”