Comparison of quasiclassical and quantum dynamics for resonance scattering in the Cl+HCl r arrow ClH+Cl reaction

Journal Article · Sun Nov 01 04:00:00 EST 1992 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.463703· OSTI ID:7227240

Jakubetz, W ^[1]; Sokolovski, D; Connor, J N.L. ^[2]; Schatz, G C ^[3]

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1. Institut fuer Theoretische Chemie und Strahlenchemie, Universitaet Wien, A-1090 Wien (Austria)
2. Department of Chemistry, University of Manchester, Manchester M13 9PL (United Kingdom)
3. Theoretical Chemistry Group, Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

We present the results of quasiclassical trajectory (QCT) and quantum centrifugal sudden hyperspherical (CSH) scattering calculations for the Cl+HCl{r arrow}ClH+Cl reaction using a semiempirical potential energy surface. In particular, we report state-to-state integral and differential cross sections in the vicinity of a transition state resonance that occurs at a total energy {ital E} of 0.642 eV. This resonance, which is labeled by the transition state quantum numbers (0,0,2), strongly perturbs the cross sections for the initial rovibrational state HCl({ital v}=1, {ital j}=5), which was therefore considered in all our calculations. For {ital E}{ge}0.680 eV, which is well removed from the resonance energy, the QCT and CSH results are in good agreement, but for {ital E} near the resonance energy, important quantum effects are found in the integral cross sections, product state distributions, and differential cross sections. The CSH integral cross sections show smooth steplike increases for {ital E}{approx}0.642 eV, which are not seen in the QCT results. Associated with these steps are increased branching to the {ital v}{prime}=0 product HCl vibrational state, and a strong propensity for the production of rotational states with {ital j}{prime}=15 and 16 for {ital v}{prime}=0. These features of the product energy partitioning are not present in the QCT results, although the correct rotational distributions are approximately recovered if the final vibrational action is constrained to match its quantum value. The CSH differential cross sections show a sudden shift from backward to sideward scattering between 0.642 and 0.660 eV, while the QCT cross sections remain backward peaked. An analysis of the number of atom--diatom encounters,'' during the course of a reactive collision, shows that there are chattering trajectories.

• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 7227240
• Journal Information: Journal of Chemical Physics; (United States), Journal Name: Journal of Chemical Physics; (United States) Vol. 97:9; ISSN JCPSA; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ANGULAR DISTRIBUTION
ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
CHEMICAL REACTIONS
CHLORINE
CHLORINE COMPOUNDS
CLASSICAL MECHANICS
COLLISIONS
COMPARATIVE EVALUATIONS
CROSS SECTIONS
DIFFERENTIAL CROSS SECTIONS
DISTRIBUTION
ELEMENTS
ENERGY
EVALUATION
HALOGEN COMPOUNDS
HALOGENS
HYDROCHLORIC ACID
HYDROGEN COMPOUNDS
INELASTIC SCATTERING
INORGANIC ACIDS
INTEGRAL CROSS SECTIONS
MECHANICS
MOLECULE COLLISIONS
NONMETALS
POTENTIAL ENERGY
PROBABILITY
QUANTUM MECHANICS
RESONANCE SCATTERING
SCATTERING