On the Role of Dipole-Dipole Coupling in Dielectric Media
- 1 July 1937
- journal article
- research article
- Published by AIP Publishing in The Journal of Chemical Physics
- Vol. 5 (7), 556-568
- https://doi.org/10.1063/1.1750074
Abstract
The mathematical treatment of dipole‐dipole coupling in my previous article on magnetism applies with but little modification to the electric case. Because of fluctuation effects, the use of the usual Lorentz local field E+4πP/3 and of the Clausius‐Mossotti formula cannot be justified except as a first approximation valid at low density. Consequently one need not accept the C‐M prediction that polar liquids should exhibit the electric analogue of ferro‐magnetism. A Gaussian approximation, or better still, a formula based on Onsager's field would never allow ferro‐magnetism. Consequently the hypothesis of hindered rotation, as in the theories of Fowler and Debye, may not be necessary to explain the absence of spontaneous polarization, as well as the non‐occurrence of much saturation curvature in strong applied fields. It is a weakness of their theory that this hypothesis cannot consistently be employed both for such purposes and to explain discontinuities in dielectric constants and specific heats at lower temperatures (e.g., 100° in HCl). It is surprising that the Clausius‐Mossotti formula works so exceedingly well as it does in nonpolar liquids, since it is theoretically valid at high densities only for an artificial model of harmonic oscillators which cannot be regarded as an accurate representation of the induced polarization. The calculations of Kirkwood on the translational fluctuation effect, causing deviations from the C‐M expression in gases, are extended to include polar molecules, and agree adequately with recent measurements of Keyes and collaborators on NH3.Keywords
This publication has 23 references indexed in Scilit:
- A quantum mechanical discussion of the cohesive forces and thermal expansion coefficients of the alkali metalsProceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences, 1937
- Electric Moments of Molecules in LiquidsJournal of the American Chemical Society, 1936
- Polarization and Dielectric Constant of LiquidsJournal of the American Chemical Society, 1936
- Time effects in the magnetic cooling method─IProceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences, 1936
- The refractive index of an ionized mediumProceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character, 1934
- Influence of Dipole Fields between Solute Molecules. II. On Molecular PolarizationJournal of the American Chemical Society, 1934
- L'interaction Entre les Atomes Magnétogènes dans un Cristal ParamagnétiquePhysica, 1934
- Dipole Rotation and the Transitions in the Crystalline Hydrogen HalidesJournal of the American Chemical Society, 1933
- THE DIELECTRIC CONSTANT OF HYDROGEN CHLORIDE FROM 85 TO 165°K.Journal of the American Chemical Society, 1931
- The Dielectric Constant of Ammonia as a Function of Temperature and DensityPhysical Review B, 1930