Computer simulation studies of anisotropic systems. VII. Pretransitional effects in nematogens

Abstract

We have studied the pretransitional behaviour at the nematic-isotropic transition for two systems by simulating the second-rank Kirkwood g -factor in the isotropic phase using the Monte Carlo technique. The Lebwohl-Lasher model was used for one nematogen while for the other the simple anisotropic intermolecular potential was replaced by a trun­cated dispersion potential. The simulated g 2 -factor is found to diverge for both potentials as the nematic-isotropic transition is approached, in accord with the anticipated increase in angular correlations. The divergence in g 2 observed for the two anisotropic potentials is compared with experiment and with the predictions of the Landau-de Gennes theory. The best agreement for both theory and experiment is found for g 2 simulated with the simple potential.