Application of the Onsager model to the theory of the dielectric constant of nonpolar liquids

摘要

In the Onsager model on the basis of statistical calculation of the cavity radius by the method proposed by Linder and Hoernschemeyer using experimental data for the radial distribution functiong(r) in liquids, the molecular polarizability changes Dgr;agr; under phase transition from gaseous to liquid state are evaluated for eight substances: noble gases, CH4, CF4, and water. For all liquids with the exception, perhaps, of helium and neon (everything depends on the accuracy of the experimental data for the dielectric constant egr; and the polarizability agr;0of noninteracting molecules in gases) Dgr;agr; proves to be positive. Contributions of dipole and overlap effects to Dgr;agr; in liquid He, Ne, and Ar are discussed on the basis of the approximate calculation of the dipole part using Slater onehyphen;electron orbitals and theoretical results for the twohyphen;body contribution to electron overlap. The Onsager model allows one to calculate also the Kirkwood fluctuation correction to the Clausiusndash;Mossotti function and values of some threehyphen;body integrals.