COMPUTER-SIMULATION STUDIES OF ANISOTROPIC SYSTEMS .20. ON THE VALIDITY OF THE MAIER-SAUPE APPROXIMATIONS FOR THE GAY-BERNE NEMATOGEN

We have explored some of the fundamental approximations contained in the Maier-Saupe theory of nematics with the aid of the results of a molecular dynamics simulation study of the Gay-Berne model mesogen which includes both anisotropic repulsive and attractive forces. In particular, we have considered the angular dependence of the potential of mean torque and the factors determining the strength of the molecular field experienced by a particle resulting from its interactions with the others in the nematic phase. We have also investigated the distribution of the intermolecular vector with respect to the director and have found that it deviates considerably from the spherical symmetry assumed in the Maier-Saupe theory. The implications of our results for the contribution of electrostatic interactions to the potential of mean torque are discussed.