Theoretical Study of Dynamics for the Abstraction Reaction H′ + HBr(v=0, j=0) → H′H + Br

Abstract

Theoretical studies of the dynamics of the abstraction reaction, H' + HBr (v=0,j=0) --> H'H + Br, have been performed with quasiclassical trajectory method (QCT) on a new ab initio potential energy surface (Y. Kurosaki and T. Takayanagi, private communication). The calculated QCT cross sections are in good agreement with earlier quantum wave packet results over most of the collision energy range from 0.1 to 2.6 eV, and the state-resolved rotational distributions of the product H'H molecule are quantitatively consistent with the experimental results. Comparisons of the QCT-calculated rotational-state-resolved cross sections on different potential energy surfaces show that the characteristics of the potential energy surface in the region far away from the minimum energy path have a large influence on the title abstraction reaction dynamics, and the indirect reactions that do not follow the minimum energy path have little influence on the differential cross sections (DCS). The DCSs are mainly governed by the direct reactions that do follow the minimum energy path, at both low and high collision energies. The degree of the rotational alignment of the product H'H molecule is strong at high collision energies, which means that the influence of the indirect reactions on the product rotational alignment is negligible, whereas the distribution of P(varphi(r)) is sensitive to the indirect reactions at high collision energies. With increasing collision energy, the polarization of the product rotational angular momentum decreases and the molecular rotation of the product prefers an in-plane reaction mechanism rather than the out-of-plane mechanism.

The Influence of Collision Energy on the Reaction H+HS→H2+S

“…As the collision energy increases, the integral cross sections reach a high value at 0.8 eV rapidly and then drop slightly after a plateau between 0.8 and 1.2 eV. This tendency is similar with the previous studies for other abstraction reactions H+HBr 25 and H+HCl. 26 The decrease of ICS for the title reaction results from the fact that the total reaction probability decreases as the collision energy increases.…”

Extraction of state-to-state reactive scattering attributes from wave packet in reactant Jacobi coordinates

“…22 The approach is similar in spirit with our earlier work using diatomic vibrational basis. 48,20 A similar L-shape grid has been used with bond coordinates in a state-to-state study of the Li+ HF reactive scattering process but with J =0. 49 The action of the angular kinetic operators on the wave packet can be evaluated straightforwardly with the angular FBR, but it complicates the evaluation of the action of the potential energy operator.…”

“…It has been shown that the TDWP approach is particularly powerful for calculating initial state selected total reaction probabilities for systems involving three or more atoms by using reactant Jacobi coordinates. [11][12][13] However, to extract S-matrix elements in a TDWP calculation, traditionally one needs to transform the wave function initially prepared in reactant Jacobi coordinates to product Jacobi coordinates, making the calculations cumbersome and potentially less accurate. [14][15][16][17][18][19] In the following discussion, we will call this approach the product coordinate based ͑PCB͒ method.…”

A six-dimensional wave packet study of the vibrational overtone induced decomposition of hydrogen peroxide

“…19 We define R as the distance between the centers of mass of the two OH diatoms, r 1 and r 2 are the two OH bond lengths, θ 1 and θ 2 are the angles between the translational Jacobi vector and the two internal diatomic vectors, and φ is the torsional angle. The coordinate system is depicted in Fig.…”

“…The interested reader is referred to Ref. 19 for a more complete description of the wave packet propagation method.…”