Local field in liquid dielectrics: A two-parameter mean field approach

In the molecular field approximation, one derives an expression of the static dielectric constant of an isotropic liquid involving renormalized expressions of the molecular dipole and polarizability. The long-range moderate attractive forces are treated as a perturbation of the short-range intense repulsions, so that two parameters λ and η describe the short-range correlations and the long-range order, respectively. On the condition of a superposition hypothesis, the model is compared in its hard-sphere limit (λ=0, η=1) with the available experimental data about a series of organic liquids and with Onsager's continuum approach.