Molecular simulation and theory of the isotropic-nematic interface

Computer simulations of a simple model of liquid crystals confined between parallel walls have been used to investigate the properties of nematic wett ing films and the planar nematic-isotropic interface. Comparison is made wi th the theoretical predictions of Onsager's density-functional theory, obta ined by numerical minimization of the appropriate free energy. Several diff erent anchoring conditions at the wall-nematic interface are investigated. The theory is known to overestimate the bulk coexistence densities, but wit h this proviso, the agreement between simulation and theory is excellent. F or the model studied, simulation and theory give density profiles which var y monotonically through the interface; the simulations also confirm the the oretical prediction that the density profile is shifted towards the nematic phase relative to the order parameter profile. The width of the interface, as measured by the order parameter profile, varies as expected with direct or tilt angle; the angle-dependence of the density profile width is smaller , and seems to be somewhat overestimated by the theory. (C) 2000 American I nstitute of Physics. [S0021-9606(00)50412-7].