Restricted orientation "liquid crystal" in two dimensions: Isotropic-nematic transition or liquid-gas (?)

Abstract

We present Monte Carlo simulation results of the two-dimensional Zwanzig fluid, which consists of hard line segments which may orient either horizontally or vertically. At a certain critical fugacity, we observe a phase transition with a two-dimensional Ising critical point. Above the transition point, the system is in an ordered state, with the majority of particles being either horizontally or vertically aligned. In contrast to previous work, we identify the transition as being of the liquid-gas type, as opposed to isotropic-to-nematic. This interpretation naturally accounts for the observed Ising critical behavior. Furthermore, when the Zwanzig fluid is extended to more allowed particle orientations, we argue that in some cases the symmetry of a q-state Potts model with q>2 arises. This observation is used to interpret a number of previous results.

6 pages. to appear in Europhysics Letters

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Cited by in corpus (20)

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• Monolayers of hard rods on planar substrates: I. Equilibrium
• Phase diagram of self-assembled rigid rods on two-dimensional lattices: Theory and Monte Carlo simulations
• Re-entrant Disordered Phase in a System of Repulsive Rods on a Bethe-like Lattice
• Critical exponents and universality for the isotropic-nematic phase transition in a system of self-assembled rigid rods on a lattice
• Entropy of fully packed hard rigid rods on $d$-dimensional hyper-cubic lattices
• Towards understanding the ordering behavior of hard needles: New analytical solutions in one dimension
• Different phases of a system of hard rods on three dimensional cubic lattice
• Phase transitions in systems of hard rectangles with non-integer aspect ratio
• A scale-bridging modeling approach for anisotropic organic molecules at patterned semiconductor surfaces
• The phase transition from nematic to high-density disordered phase in a system of hard rods on a lattice
• Polydispersed rods on the square lattice
• Absence of logarithmic divergence of the entanglement entropies at the phase transitions of a 2D classical hard rod model
• Diffusion dynamics and steady states of systems of hard rods on the square lattice
• The main transition in the Pink membrane model: finite-size scaling and the influence of surface roughness
• Nematic and gas-liquid transitions for sticky rods on square and cubic lattices
• The effect of the lateral interactions on the critical behavior of long straight rigid rods on two-dimensional lattices
• Semi-flexible trimers on the square lattice in the full lattice limit