Quantal study of the exchange reaction for N+N2 using an ab initio potential energy surface

Abstract

The N + N2 exchange rate is calculated using a time-dependent quantum dynamics method on a newly determined ab initio potential energy surface (PES) for the ground 4A" state. This ab initio PES shows a double barrier feature in the interaction region with the barrier height at 47.2 kcal/mol, and a shallow well between these two barriers, with the minimum at 43.7 kcal/mol. A quantum dynamics wave packet calculation has been carried out using the fitted PES to compute the cumulative reaction probability for the exchange reaction of N + N2(J=0). The J -K shift method is then employed to obtain the rate constant for this reaction. The calculated rate constant is compared with experimental data and a recent quasi-classical calculation using a LEPS PES.Significant differences are found between the present and quasiclassical results. The present rate calculation is the first accurate 3D quantal dynamics study for N + N2 reaction system and the ab initio PES reported here is the first such surface for N3.

Atom—Diatom Collision Processes: Rovibrationally Detailed Cross Sections For Models

“…Some comparisons concerning vibration-translation energy exchange and dissociation significantly put in evidence the general agreement with data in this work obtained on a more accurate PES, but also some differences, particularly on high lying rovibrational states, which are determinant in recombination [29]. For nitrogen system, exchange rate has been compared with some global experimental and computational results, with quite good agreement [8,20]. Concerning oxygen, an interesting comparison can be appreciated with approximate experimental multiquantum transitions, showing qualitative agreement, with details described in [13].…”

“…Concerning nitrogen, the PES adopted is the well known LEPS of Lagana' et al [19], which is a semiempirical surface. At the time of calculations no other PES was available, while now there are different examples of more refined surfaces [20,21], in particular the PES of Varandas and collaborators [22], on which new sistematic calculations will be soon performed. The calculations in the database have a minimum density of 24000 trajectories per Å of impact parameter and per eV of translational energy in the interval 0.001 to 3 eV, and 4 times less for higher energy up to 10 eV.…”

Direct Detection of NO Produced by High-Temperature Surface-Catalyzed Atom Recombination

“…This rate coefficient is expected to decrease with decreasing temperature [14,15]. The reaction of concern for our experiments is 14 reaction should be very similar and the generation of 15 N is statistically more probable from 15 N 15 N than 14 N 15 N. Therefore, the reaction rate coefficient for 14 N 14 N 15 N ! 15 N 14 N 14 N should be no higher than the limiting value determined by Back and Mui [13] for 14 N 15 N 15 N !…”

Analytical potential energy surfaces for N3 low-lying doublet states

“…30 To study the same exchange reaction, Wang et al determined an ab initio PES for N 3 ground 4 AЉ state with many body expansion using the Jacobi coordinate. 31 They carried out time-dependent quantum dynamics study on this surface to compute the reaction probability and study the rich resonance structure. 32,33 Babikov et al 34 constructed the ground doublet electronic state surface of N 3 by a three-dimensional spline fit using adiabatically adjusted principal-axes hyperspherical coordinates and predicted the vibrational spectra of the pure nitrogen ring.…”