Close coupling scattering calculations have been conducted for the para spin modification of H<sub>2</sub>-{He, Ne and Ar}. The XC(fit) potential energy surfaces for H<sub>2</sub>-Ne and H<sub>2</sub>-Ar have been used for calculations for these two systems, while a newly fitted version of the Schaefer and Kohler potential energy surface was used for the H<sub>2</sub>-He system. The fitting procedure employs nine modified Lennard-Jones oscillator functions to describe accurately 90% of the original tabulated potential energy surface to better than 12% error. The scattering calculations for H<sub>2</sub>-Arfailed at higher energies due to the presence of a previously undocumented potential energy surface turn-over at R less than 1. 0 Angstroms. Manifold-to-manifold v=1 vibrational relaxation calculations for each of these systems are compared with other experimental and theoretical calculations. These comparisons demonstrate a common discrepancy between previous calculations and the current calculations for each system. The current vibrational relaxation rate constants are generally too small when compared to low temperature values of Audibert et al. and Orlikowski, and the high temperature values obtained by Flower et al. and Dove andTeitelbaum. The current calculations indicate the presence of a dramatic up-turn in the low temperature H<sub>2</sub>-He rate constants. Other experimental and theoretical treatments do not exhibit this same up-turn, which is puzzling. A set of follow-up calculations featuring a larger basis set (such as the {16,12,10,8} Flower et al. basis set) and a larger manifold of included relaxation pathways are needed to improve these calculations.
| Identifer | oai:union.ndltd.org:WATERLOO/oai:uwspace.uwaterloo.ca:10012/1227 |
| Date | January 2001 |
| Creators | Weir, Douglas |
| Publisher | University of Waterloo |
| Source Sets | University of Waterloo Electronic Theses Repository |
| Language | English |
| Detected Language | English |
| Type | Thesis or Dissertation |
| Format | application/pdf, 814307 bytes, application/pdf |
| Rights | Copyright: 2001, Weir, Douglas. All rights reserved. |
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