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Journal of Chemical Physics

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Dielectrics, Statistical mechanics


An approximate theory for the dielectric constant ℇ of a dense polar fluid was derived by Ramshaw, Schaefer, Waugh, and Deutch (RSWD). In the present article, the RSWD theory is generalized and made rigorous by another method of derivation. The result is a rigorous expression for ℇ which differs from the RSWD expression by the presence of a fluctuation term. Both the rigorous expression and the RSWD expression are then specialized to the Onsager model. It is found that the rigorous expression for ℇ reduces to the Onsager equation, but that the RSWD expression does not because the fluctuation term is nonzero (and nonnegligible) for the Onsager model. The well-known discrepancy between the Onsager equation and the theory of Harris and Alder is found to have the same origin.


Article appears in the Journal of Chemical Physics ( and is copyrighted (1974) by the American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.

*At the time of publication John Ramshaw was affiliated with Applied Theory, Incorporated, Los Angeles, California



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