Quantum scattering studies of long-lived resonances for the reaction Ne+H+2→NeH++H

Abstract

Theoretical studies of the reactivity and spectroscopy of H+CO=HCO. I. Stabilization and scattering studies of resonances for J=0 on the Harding a b i n i t i o surfaceThe bending-corrected rotating linear model (BCRLM) is used to investigate the reaction of neon with Hi (v=0-3) using three different fits to the ab initio potential-energy surface computed by Urban, Jaquet, and Staemmler. Numerous long-liy~d scattering resonances are found for each surface. The number and position of these scattering resonances are found to be sensitive to the relatively small differences among these three surfaces. These BCRLM results demonstrate how the rich resonance structure that appears in the partial cross sections is washed out in the total cross section. The integrated rates for reactivity from v=O and 1 are nearly identical for all three potential-energy surfaces over a wide range of temperatures. However, the integrated rates from v=2 and 3 exhibit significant differences among the potential-energy surfaces. A vibrationally adiabatic hyperspherical model of the trapped resonance states provides insight into the nature and contribution of these resonances to reactive scattering. The more accurate of the three fits to the ab initio potential-energy surface (obtained using the functional form of Aguado and Paniagua) is also used to obtain converged results for total angular momentum J=O employing the adiabatically adjusting, principal axis, hyperspherical (APH) formulation of Pack and Parker for quantum reactive scattering in three dimensions (3D). An eigenlifetime analysis of these 3D scattering results reveals numerous resonances with lifetimes of 1 ps or more. While this resonance structure is sensitive to the details of the potential energy surface, with appropriate Gaussian averaging over the total scattering energy, the cumulative reaction probabilities (CRPs) are not very sensitive to changes in the potential energy surface. Moreover, these quantum CRPs agree rather well with CRPs predicted using variational Rice-Ramsperger-Kassel-Marcus (RRKM) calculations.2728

Nonadiabatic quantum reactive scattering calculations for the O(1D)+H2, D2, and HD reactions on the lowest three potential energy surfaces

“…Also, resonance structures in the cumulative reaction probability have been found for other barrierless reactions such as H ϩO 2 , 47-50 HeϩH 2 ϩ , 51 and NeϩH 2 ϩ . 52,53 B. O" 1 D…¿D 2 Figure 5 shows the calculated total reaction probabilities for the O( 1 D)ϩD 2 (vϭ0,jϭ0,1, and 2)→ODϩD reaction as a function of the total energy. Despite that there exists a large difference in mass, the behavior of the calculated total reaction probabilities is essentially the same as that of O( 1 D)ϩH 2 .…”

Interpolation and fitting of potential energy surfaces: Concepts, recipes and applications

“…In the case of scattering calculations one would think that this might be a small error of 0.006 eV, which is better than the accuracy of the fit. BCRLM reaction probabilities [426] for the three fits show, however, that the average height of the strongly oscillating reaction probability Pg--+ o varies between 0.05 (Fit 1) and 0.15 (Fit 3). ..…”

“…Detailed information of the three different fits and the minimum energy paths is given in [125]. The differences in the fits are seen more clearly when these PESs are used in dynamics calculations: bound state calculations for the rovibrational levels of NeHt and its isotopomeres, quantum scattering studies of long lived resonances for the reaction Ne + Ht ~ NeH+ + H [426] and quasiclassical and approximate quantum mechanical (R-IOSA) studies of the intramolecular isotope effects in proton transfer: Ne + HD+ ~ NeH+ (NeD+) + D (H) [427].…”

Isotopic effects on the stereodynamics for the reactions

“…In 1993, an accurate PES of the ground state of the NeH þ 2 reactive system was presented by Pendergast et al [1] using the coupled-electron approach, whereafter more studies have been conducted based on this PES. Kress et al [2] reported the state-tostate reaction probabilities for zero total angular momentum based on the bending-corrected rotating linear model using quantumdynamics calculations. State-selected integral cross sections as a function of energy using the coupled-states approximation were reported by Gilibert and co-workers [3,4].…”