A contribution to the theory of the dielectric constant of polar liquids

Abstract

Some simplifications used in Onsager's theory on the dielectric constant of pure liquids are considered. At first, instead of a spherical, an ellipsoidal shape of the molecules is attempted and the cavity field and reaction field of a dipole are computed in this case. It appears that the reaction field of a dipole in an ellipsoidal cavity is smaller than the reaction field in a spherical cavity of the same volume if the longest axis is in the direction of the dipole. In the case that the shortest axis is in the direction of the dipole, the reaction field is greater than in a spherical cavity. Also a discussion on the radius of the cavity is given. A model is assumed in which for the polarisability effects the continuous environment begins at a distance equal to the radius of the molecules while for the influance of the dipolar interaction the continuous environment begins at twice as great a distance.