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Classical and quantum centrifugal decoupling approximations for HCl–Ar

Tarr, Susan M. and Rabitz, Herschel and Fitz, D. E. and Marcus, R. A. (1977) Classical and quantum centrifugal decoupling approximations for HCl–Ar. Journal of Chemical Physics, 66 (7). pp. 2854-2859. ISSN 0021-9606. http://resolver.caltech.edu/CaltechAUTHORS:TARjcp77

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Abstract

The centrifugal decoupling approximation previously employed in quantum mechanics is extended to classical mechanics. Both classical and quantum centrifugal decoupling (CCD and CD, respectively) calculations are performed for HCl–Ar. Total cross sections are obtained from the CCD and CD calculations. The CCD and CD total cross sections are shown to be in good agreement with the corresponding exact classical trajectory (EC) and close coupled (CC) cross sections, respectively. The conservation of the projection (Omega) of the rotational angular momentum along the body-fixed z-axis is studied as a possible explanation for the success of the CCD and CD approximations in predicting total cross sections. By examining the CC body-fixed S-matrix elements and studying the behavior of Omega during the course of an exact classical trajectory, it is found that Omega is conserved only under very limited conditions. Detailed examination of the calculations shows that the CD approximation may be good even when Omega varies rapidly.


Item Type:Article
Additional Information:Copyright © 1977 American Institute of Physics. (Received 23 September 1976) We wish thank S. Green for providing with CC cross sections and transformed S-matrix elements and S. Augustin for many helpful comments. We also thank D. Kouri and R. Pack for providing information on their recent work prior to publication. Supported in part by grants from the National Science Foundation, the Energy Research and Development Administration, and the Donors of the Petroleum Research Fund administered by the American Chemical Society. [H.R. was an] Alfred P. Sloan Fellow; Camille and Henry Dreyfus Fellow.
Subject Keywords:HYDROCHLORIC ACID, ARGON, ATOM–MOLECULE COLLISIONS, ANGULAR MOMENTUM, ROTATIONAL STATES, TOTAL CROSS SECTIONS
Record Number:CaltechAUTHORS:TARjcp77
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:TARjcp77
Alternative URL:http://dx.doi.org/10.1063/1.434343
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10370
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:01 May 2008
Last Modified:26 Dec 2012 09:59

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