  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.
