Analysis of the Resonance in the Three Dimensional F + H₂ Reaction

Abstract

Quantum mechanical resonance structure in the three‐dimensional F + H2 reaction is analyzed in several ways: wavefunction density and flux maps in the transition state region, Argand diagrams which show the energy variation of S‐matrix elements, the time delay computed from the energy derivative of the phase of S‐matrix elements, and the energy variation of nodes in the product channel translational wavefunctions. In addition, differential cross sections for the v = 0 → v' = 2 reaction, computed from quantum reaction probabilities in an optical model, are compared with experimental data. These results are correlated with other recent theoretical results on this reaction, and some remaining theoretical problems are discussed.

Study of quantum resonance behavior in the atomic chlorine + molecular hydrogen .fwdarw. hydrogen chloride + atomic hydrogen reaction

“…A similar gradual shift of the maximum of the reaction probability as a function of l with increasing energy is also observed, though to a much less marked extent, in the results of classical trajectory calculations on the same potential energy surface.14 The effects of quantum-mechanical resonances on reactive scattering cross sections have been extensively discussed, especially for the F + H2 -*• HF + H reaction. 5,6 In this case a qualitatively similar, though quantitatively more marked, behavior of the / (or J) dependence of the reaction probability was noted,5 in connection with the resonance in the F + H2(y = 0) -* HF(u' = 2) + H reactive cross section. In the present case the change in the l HCl(u' = 0) + H calculated by using the BCRLM method at different energies.…”

“…Despite these conclusions, however, the "reaction probability surface" for the reaction (Figure 6) shows features of the type which have in the past been taken to be characteristic of resonance behavior. 5 The energy dependence of the differential reactive cross section is also erratic over the relevant energy range. These features may be regarded as displaying the remnants of the nearly completely quenched resonance behavior in the approximate three-dimensional quantum-mechanical calculations.…”

Observation of a transition state resonance in the integral cross section of the F+HD reaction

“…Of course earlier studies on other surfaces has yielded reactive resonances trapped near the saddlepoint. 25 While such resonances have not been reported on the SW-surface there is no reason to believe that they will not exist. Transition state resonances appear on all reasonable surfaces and appear to be quite robust with respect to details of the PES and dynamical approximation.…”

An improved potential energy surface for F+H2→HF+H and H+H′F→HF+H′

“…2 that is corrected in the new surface of this paper is the barrier to the exchange reaction H + FH' -+ HF + H'. This was corrected by adding to the LEPS-type potential a barrier term of the form (7) where RI and R3 are the two HF bond distances, and (JHFH is the HFH bond angle. This form is similar to that used by Last and Baer in their diatomics-in-moleculesplus-three-center-terms method.…”