COMPUTER-SIMULATION OF LIQUID-CRYSTALS

Computer simulations. using the molecular dynamics and Monte Carlo tec hniques, and employing simple molecular models, yield insight into gen eral features of phase equilibria, structure. and dynamics of liquid c rystals. Here, results are reported from extensive simulations of the Gay-Berne family of molecular models, in which potential parameters ar e adjusted to vary the molecular length-to-width ratio in a systematic way. Attention is paid to the characterization of nematic, smectic-A and smectic-B phases as functions of these parameters. A simulation st udy of the approach to the isotropic-nematic phase transition, using a large system size and lengthy runs on the T3D parallel supercomputer, is described. Spatially long-ranged collective orientational correlat ions develop in the isotropic phase, close to the transition. The dire ct correlation function has been calculated for these systems, and rem ains short-ranged, as expected, as the transition is approached. The s imulation results are compared with the density functional analysis of isotropic instability relative to the nematic phase.