Nematic-Nematic Phase Transition as a Consequence of Orientational-Translational Order Parameters Interaction

Abstract

A model of smectic A liquid crystal with nonlinear competiting orientational and translational order parameters in the eight-dimensional control parameters space is developed. Topological analysis is performed which allows to construct all possible, at least two-dimensional, phase diagrams of the model under consideration. It is shown that orientational and translational interactions can be the only reason leading to the existence of two different nematic phases and isostructural phase transitions of the nematic-nematic type which were observed in some mesogeneous compounds.