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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/3939

Title: ON THE EFFECT OF CENTRIFUGAL STRETCHING ON THE ROTATIONAL PARTITION-FUNCTION OF AN ASYMMETRIC-TOP
Authors: MARTIN, Jan
FRANCOIS, Jean-Pierre
GIJBELS, R
Issue Date: 1991
Publisher: AMER INST PHYSICS
Citation: JOURNAL OF CHEMICAL PHYSICS, 95(11). p. 8374-8389
Abstract: Correction terms (up to third order in temperature) for the effect of centrifugal distortion on the rotational partition function of linear molecules, spherical, symmetric, and asymmetric tops are evaluated by means of the classical partition function. It is shown that for the linear, spherical, and symmetric cases, the expressions thus obtained differ from the exact quantum expressions only in the absence of a very small constant correction term. It is then proposed that the partition function for a nonrigid asymmetric top, for which no exact expression has as yet been derived, be evaluated as the product of Watson's asymptotic expansion for the rigid rotor and the centrifugal correction factor derived in the present work. Numerical comparison with direct numerical summation shows that, even for troublesome cases, this approximation holds very well even at 2000 K. Similar performance is observed for the heat content function, except for pathological cases at high temperatures. In the rigid-rotor case, Watson's asymptotic series holds very well. As an example application, pilot calculations have been performed on the thermodynamic functions of water and formaldehyde. The present method yields functions in excellent agreement with those obtained by direct rovibrational summation, whereas computer-time requirements are reduced by 3 or 4 orders of magnitude.
Notes: UNIV INSTELLING ANTWERP,INST MAT SCI,DEPT CHEM,B-2610 WILRIJK,BELGIUM.MARTIN, JML, LIMBURG STATE UNIV CTR,DEPT SBM,UNIV CAMPUS,B-3590 DIEPENBEEK,BELGIUM.
URI: http://hdl.handle.net/1942/3939
DOI: 10.1063/1.461265
ISI #: A1991GR66500062
ISSN: 0021-9606
Type: Journal Contribution
Appears in Collections: Research publications

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