STUDIES OF NEMATIC-ISOTROPIC TRANSITION FOR A GAY-BERNE FLUID USING THE 2ND VIRIAL APPROXIMATION

In this paper we use the second virial approximation to study the nema tic-isotropic (N-I) transition for a Gay-Berne liquid for a broad rang e cf parameters. For Gay-Berne hard Gaussian overlap (HGO) fluid parti cles we found that a N-I transition exists as a function of density fo r all length to breadth ratios kappa > 4, in reasonable agreement with other theoretical studies and results of Monte Carlo simulations. For the full Gay-Berne potential (GB) the location of the N-I transition as a function of density for different temperatures was studied for se veral values of shape and energy anisotropy parameters kappa and kappa '. It was shown that the transition temperature increases or the trans ition density decreases with increasing kappa and/or decreasing kappa' . Wherever the molecular dynamics (MD) or Monte Carlo (MC) data were a vailable, comparison was made. For each system, coexistence density an d pressure were calculated, and, wherever possible, also compared with MC or MD data to show qualitative agreement. The reported study is co nsidered to be a first step in the calculation of N-I transition for r igid liquid crystal(LC) molecules.