Computer simulation studies of anisotropic systems .26. Monte Carlo investigations of a Gay-Berne discotic at constant pressure

The majority of molecules which form liquid crystals are elongated in shape. However, disk shaped molecules have also been shown to exhibit liquid crystalline phases. In this paper we report a series of constant pressure Monte Carlo simulations of model discotic molecules. We have used the Gay-Berne potential, which is in essence an anisotropic version of a shifted Lennard-Jones potential, to model the interactions between the disks. Initially we studied a system of 512 molecules over a range of pressures to determine the mesophases formed and to construct the phase diagram. The system was found to exhibit isotropic, nematic, and columnar phases. We have also studied a larger system of 2000 molecules at a single pressure to calculate more accurately the distribution functions used to describe the translational and orientational order within the various phases. (C) 1996 American Institute of Physics.