Solute diffusion in nematic liquid crystalline fluids was studied using Enskog kinetic theory and molecular dynamics simulation. The liquid crystalline solvent was modelled by perfectly aligned hard ellipsoids of revolution, and the solute was either a spherical or ellipsoidal particle. The diffusion coefficient was calculated for a range of solvent densities and solute and solvent aspect ratios and sizes. The kinetic theory permitted the study of various parameters that were easily compared with simulation or experiment. The validity of the kinetic theory, and its range of applicability was tested against the computer simulations. The main focus of the study was the anisotropy of diffusion, defined as the ratio of diffusivity in directions parallel and perpendicular, respectively, to the solvent director. If the pair correlation function at contact surface was taken to be isotropic, Enskog kinetic theory finds that the anisotropy in diffusion was independent of density and collision frequency, and depended only on size and shape of colliding particles. This result was confirmed by the simulations.

Tracer Diffusion in Perfectly Aligned Liquid Crystalline Phases Kinetic Theory and Molecular Dynamics Simulations. Khare, A.A., Kofke, D.A., Evans, G.T.: Molecular Physics, 1997, 91[6], 993-1003