First-order phase transitions in two-dimensional off-lattice liquid crystals

TL;DR

This paper demonstrates that a purely repulsive, short-range off-lattice liquid crystal model in two dimensions can exhibit a first-order isotropic-to-nematic phase transition, confirmed through theory and simulation.

Contribution

It introduces a simple off-lattice liquid crystal model that undergoes a first-order phase transition, combining mean-field theory and simulations for validation.

Findings

First-order isotropic-to-nematic transition observed

Large density gap between coexisting phases

Confirmed by simulations and finite-size scaling

Abstract

We consider an off-lattice liquid crystal pair potential in strictly two dimensions. The potential is purely repulsive and short-ranged. Nevertheless, by means of a single parameter in the potential, the system is shown to undergo a first-order phase transition. The transition is studied using mean-field density functional theory, and shown to be of the isotropic-to-nematic kind. In addition, the theory predicts a large density gap between the two coexisting phases. The first-order nature of the transition is confirmed using computer simulation and finite-size scaling. Also presented is an analysis of the interface between the coexisting domains, including estimates of the line tension, as well as an investigation of anchoring effects.