PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS

The nematic-isotropic phase transition is investigated for a sample in the shape of a slab of thickness d, using a self-consistent model. The interacting potential is given by a sum of the direct interaction of a given nematic molecule with the substrate and of one with the other nematic molecules due to the presence of the limiting surface. The variation of second- and fourth-rank long-range order parameters with temperature is investigated. To describe the behaviour of second- and fourth-rank order parameters at the surfaces and its profile inside the sample, a model based on the Maier-Saupe model including P-4 interaction is used. In conclusion, we show the existence of a boundary layer in which the second- and fourth-rank order parameters can be greater or smaller than the one in the bulk. (c) 2006 Elsevier B.V. All rights reserved