Interfacial anisotropy in the transport of liquid crystals confined between flat, structureless walls: A molecular dynamics simulation approach

Molecular dynamics simulations of uniaxial Gay-Berne ellipsoids as prolate liquid crystal molecules confined between two flat, structureless walls have been carried out in order to investigate anisotropy in their dynamic properties. Several physical quantities are profiled as a function of distance from a wall. The walls stimulate ellipsoids into different behaviors from those of the bulk system. The profiles of self-diffusion coefficients, which are distinguished in each direction of a director-based coordinate system, show that the ellipsoids are more diffusive parallel to the walls and less diffusive perpendicular to the walls with decreasing distance from the walls. According to the self-rotation coefficient and rotational viscosity profiles, ellipsoids are easy to rotate parallel to the walls and hard to rotate in the plane perpendicular to the walls. The analyses of velocity autocorrelation functions, angular velocity autocorrelation functions, director angular velocity autocorrelation functions, and their spectra are useful for the investigation of anisotropy near the walls. We conclude that the flat, structureless wall not only prevents ellipsoids from diffusing and rotating in the plane perpendicular to the walls, but also stimulates them to diffuse and rotate in the plane parallel to the walls.