Computer simulation studies of anisotropic systems

Abstract

The Lebwohl-Lasher model of a nematogen provides a simple system with which to study the order-disorder transition and to examine the properties of the nematic phase. We have investigated the model containing 203 particles over a small temperature range characteristic of that for real nematogens using the Monte Carlo method to evaluate the internal energy, the heat capacity and the second rank orientational order parameter. Our results are in reasonable agreement with those of other simulations and are compared with the predictions of theories based on a cluster expansion of the free energy. The temperature dependence of the order parameter is used to investigate the validity of the singlet orientational distribution function predicted by the Maier-Saupe theory. The potential of mean torque is found to be linear in the order parameter as required by the theory although the orientational free energy is in error. The simulated properties are in reasonable but not complete accord with those of a real nematog...