MICROSCOPIC FREE-ENERGY FUNCTIONAL FOR POLARIZATION FLUCTUATIONS - GENERALIZATION OF MARCUS-FELDERHOF EXPRESSION

A microscopic expression for the free energy functional for polarization fluctuations in a dipolar liquid in the presence of an external field is derived from the first principles by using the density functional theory. The microscopic expression is shown to reduce to the well known free energy expressions of Marcus and Felderhof in the appropriate limits. The microscopic free energy functional can be especially useful to describe those dynamical processes when intermolecular correlations are important.