Computer simulation study of a biaxial nematogenic lattice model associated with a two-dimensional lattice

We report here the mean field (ME) and Monte Carlo (MC) simulation study of a nematogenic lattice model; it involves particles possessing D-2/i, symmetry, whose centres of mass are associated with a two-dimensional square lattice, while particle orientations belong to ordinary three-dimensional space; the pair potential, restricted to their nearest neighbours, is defined by a London-De Boer-Heller dispersion interaction. Both MF and MC show the existence of a low-temperature biaxial phase, followed by a uniaxial one at higher temperature, probably surviving at all higher temperatures. In the biaxial region MF yields results in only qualitative agreement with MC; the agreement recognizably improves in the following uniaxial region, at higher temperatures. (C) 2004 Elsevier B.V. All rights reserved.