Dielectric properties of polar liquids. The model of hindered molecular rotation

A simple phenomenological model of hindered molecular rotation is proposed to describe the temperature dependence of the Kirkwood factor g(k)(T) of polar liquids. The model allows, at least qualitatively, various types of the g(k)(T) function behavior to be explained by relating them to the difference in the structure ("shape") of molecules forming liquid. The model is based on an assumption that the short-range order in dense systems is produced by short-range sterical forces, whereas the long-range electrostatic interactions "are adjusted" to the short-range order specified by the shape of molecules and are responsible for the orientational (dipole) structure of liquid. Then, the approximation of interaction between nearest neighbors and analogy with the theory of intramolecular rotation are used to derive asymptotic formulae relating g(k)(T) to the barriers to intermolecular rotations in liquid.