Computer simulation studies of anisotropic systems

Abstract

We have studied the surface behaviour of the Lebwohl-Lasher model nematogen using the Monte Carlo technique of computer simulation. Two states of the nematogen have been investigated, one with normal periodic boundary conditions and the other with boundary conditions employed for just two dimensions thus forming two free surfaces orthogonal to the third dimension. We have determined the variation of the internal energy and the second rank orientational order parameter, associated with individual layers, with their distance from the surface, as a function of the temperature. The order in the surface is found to be less than in the bulk nematogen although this difference is far less for the isotropic phase than for the nematic. This suppression of the surface orientational order is in accord with the surface tension simulated for the nematogen. Thus the surface tension decreases rapidly with increasing temperature in the nematic mesophase but then is essentially independent of temperature in the isotropic p...