Optical and structural anisotropy of a uniaxial nematic consisting of biaxial molecules with internal rotation

Abstract

A relation is established between the refractive indices of a uniaxial nematic liquid crystal (LC) consisting of biaxial molecules with internal rotation and the properties of molecules and their structural ordering. It is shown that the correlation between the conformation degree of freedom associated with internal rotation of π-conjugate molecular fragments and the orientation degrees of freedom of the molecules as a whole leads to the existence of two mixed parameters of orientation-conformation order, which contribute to the optical anisotropy of the LC along with the parameters of the conformation and orientation order of the molecules. The effect of the correlation of the molecular degrees of freedom on the values of these order parameters and the properties of molecular polarizability is analyzed. The dependence of the polarizability of molecules on their orientation ordering in the LC is explained.