Quantum mechanical reactive scattering for planar atom plus H2 * diatom systems. II. Accurate cross sections for H+H2 *
- 1 December 1976
- journal article
- research article
- Published by AIP Publishing in The Journal of Chemical Physics
- Vol. 65 (11), 4624-4641
- https://doi.org/10.1063/1.432917
Abstract
The results of an accurate quantum mechanical treatment of the planar H+H2 exchange reaction on a realistic potential energy surface are presented. Full vibration–rotation convergence was achieved in the calculations, and this, together with a large number of auxiliary convergence and invariance tests, indicates that the cross sections are accurate to 5% or better. The reactive differential cross sections are always backward peaked over the range of total energies from 0.3 to 0.65 eV. Nonreactive j=0 to j′=2 cross sections are backward peaked at low energy (0.4 eV) shifting to sidewards peaking for E≳0.5 eV. Quantum symmetry interference oscillations are very significant in the j=0 to j′=2 para‐to‐para cross sections for E?0.6 eV. Reactive integral cross sections show two distinct kinds of energy dependence. At low energy (<0.5 eV), barrier tunneling gives them a largely exponential energy dependence while above 0.5 eV (the effective threshold energy) the cross sections vary nearly linearly. Comparison of collinear and coplanar transition probabilities indicates similar 1D and 2D energy dependence but with a shift in energy from 1D to 2D due to bending motions in the transition state. An analysis of rotational distributions indicates surprisingly good correspondence with temperaturelike distributions. The results of a one‐vibration‐approximation calculation are examined, and errors of as much as three orders of magnitude are found at some energies. Shapes of angular distributions are, however, accurately predicted by this approximate method. Additional analyses include comparisons with previous distorted wave and coupled‐channel results, and calculations of thermal rate constants.Keywords
This publication has 40 references indexed in Scilit:
- Theoretical studies of H+H2 reactive scatteringThe Journal of Chemical Physics, 1974
- Role of direct and resonant (compound state) processes and of their interferences in the quantum dynamics of the collinear H + H2 exchange reactionThe Journal of Chemical Physics, 1973
- Classical Trajectory Studies on Planar Reactive H + H2The Journal of Chemical Physics, 1972
- Quantum Calculations of Planar Reactive H+H2. II. ApplicationThe Journal of Chemical Physics, 1972
- Quantum Calculations of Planar Reactive H+H2. I. TheoryThe Journal of Chemical Physics, 1972
- Atom-Molecule Reaction D+H2 → HD+H Studied by Molecular BeamsThe Journal of Chemical Physics, 1972
- Close-Coupling Technique for Chemical Exchange Reaction of the Type A+BC→AB+C. H+H2→H2+HThe Journal of Chemical Physics, 1971
- Opacity Analysis of Inelastic Molecular Collisions. IV. Statistical Aspects of Rotational Excitation TheoryThe Journal of Chemical Physics, 1970
- On the Theory of Chemical-Reaction Cross Sections. II. Application to the H + H2 ReactionThe Journal of Chemical Physics, 1967
- Potential Energy Surface for H3The Journal of Chemical Physics, 1964