Modern Approaches to Gas-Phase Quantal Molecular Reactions

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9314320 Neuhauser Univ. Cal. Los Angeles This project in diatom-diatom reactive scattering theory is supported by the NSF Theoretical and Computational Chemistry Program. Exact, coupled-channel, state-to-state, quantum scattering, calculations will be carried out for gas phase reactions of diatomic molecules taking explicit account of all six degrees of internal freedom. Improved computational methods will be developed, in particular, a time-dependent and an equivalent time-independent flux-amplitude method, use of absorbing potentials, and an improved filter algorithm for the accurate computation of eigenvectors whose eigenvalues lie within a selected range. The first application of the theory will be to the reaction of molecular hydrogen with the hydroxyl radical. This research project develops improved computational methods for predicting the detailed behavior of a very simple chemical reaction. Rigorous quantum mechanical calculations will be carried out for a four-atom system. The goal is to obtain a detailed and precise picture of the atomic events that occur. This fundamental knowledge, which is difficult and expensive to extract from laser spectroscopy and other laboratory experiments, provides detailed information that serves to test various simplifying mathematical approximations used for practical calculations for gas phase reactions of larger molecules. The reaction of molecular hydrogen with the hydroxyl radical is itself of interest because it is an important step in the chain reaction that occurs during the combustion of hydrogen gas.