Monte Carlo Simulations of Novel Biaxial Ordering in Systems of Uniaxially Interacting Rod-like Ellipsoids

TL;DR

This study uses Monte Carlo simulations to demonstrate that pure uniaxial rod-like ellipsoids can spontaneously form biaxial liquid crystalline phases due to dipolar interactions, revealing new phase behaviors.

Contribution

It provides the first robust simulation evidence of biaxial phases arising purely from uniaxial interactions in rod-like ellipsoids, highlighting the role of dipolar forces.

Findings

Dipolar interactions induce biaxial phases in uniaxial ellipsoids.

Low aspect ratio ellipsoids form tilted biaxial smectic phases.

High aspect ratio ellipsoids require terminal dipoles for biaxial ordering.

Abstract

The minimal ingredient to generate a biaxial liquid crystalline ordering is usually considered to be the strongly biaxial interactions breaking the cylindrical symmetry of the uniaxial molecules. Although there is no fundamental reason to forbid a biaxial ordering of pure uniaxial origin, it has been a long standing problem to find a robust demonstration of such phenomenon in systems of rod-like particles. We report here off-lattice Monte Carlo simulations of some new model systems of polar achiral rodlike ellipsoids which spontaneously exhibit novel biaxial smectic phases of pure uniaxial origin. We show that dipolar interactions can generate different biaxial phases of pure uniaxial origin in systems of cylindrically symmetric Gay-Berne ellipsoids for an wide variety of length-to-width ratios. The systems of ellipsoids with low length-to-width ratios exhibit highly tilted biaxial smectic phases in the presence of central axial dipoles. In case of ellipsoids having high length-to-width ratio, the generation of a biaxial phase requires the presence of two parallel axial terminal dipoles. In addition, the phases also exhibit fascinating ferroelectric or striped ordering of the dipolar ellipsoids.