Issue
EPL
Volume 78, Number 2, April 2007
Article Number 20003
Number of page(s) 5
Section General
DOI http://dx.doi.org/10.1209/0295-5075/78/20003
Published online 27 March 2007
EPL, 78 (2007) 20003
DOI: 10.1209/0295-5075/78/20003

On the orientational ordering of long rods on a lattice

A. Ghosh and D. Dhar

Department of Theoretical Physics, Tata Institute of Fundamental Research - Homi Bhabha Road, Mumbai 400 005, India

ananda@theory.tifr.res.in
ddhar@theory.tifr.res.in

received 13 November 2006; accepted in final form 27 February 2007; published April 2007
published online 27 March 2007

Abstract
We argue that a system of straight rigid rods of length k on a square lattice with only hard-core interactions shows two phase transitions as a function of density $\rho $ for $k\geqslant 7$. The system undergoes a phase transition from the low-density disordered phase to a nematic phase as $\rho $ is increased from 0 at $\rho =\rho _{c1}$, and then again undergoes a re-entrant phase transition from the nematic phase to a disordered phase at $\rho =\rho _{c2} < 1$.

PACS
05.50.+q - Lattice theory and statistics (Ising, Potts, etc.).
64.70.Md - Transitions in liquid crystals.

© Europhysics Letters Association 2007