Numerical study of surface-induced reorientation and smectic layering in a nematic liquid crystal

Surface-induced profiles of both nematic and smectic order parameters in a nematic liquid crystal, ranging from an orienting substrate to "infinity", were evaluated numerically on base of an extended Landau theory. In order to obtain a smooth behavior of the solutions at "infinity" a boundary energy functional was derived by linearizing the Landau energy around its equilibrium solutions. We find that the intrinsic wave number of the smectic structure, which plays the role of a coupling between nematic and smectic order, strongly influences the director reorientation. Whereas the smectic order is rapidly decaying when moving away from the surface, the uniaxial nematic order parameter shows an oscillatory behavior close to the substrate, accompanied by a non-zero local biaxiality.Comment: LaTeX, 17 pages, with 4 postscript figure

External and intrinsic anchoring in nematic liquid crystals: A Monte Carlo study

We present a Monte Carlo study of external surface anchoring in nematic cells with partially disordered solid substrates, as well as of intrinsic anchoring at free nematic interfaces. The simulations are based on the simple hexagonal lattice model with a spatially anisotropic intermolecular potential. We estimate the corresponding extrapolation length $b$ by imposing an elastic deformation in a hybrid cell-like nematic sample. Our estimates for $b$ increase with increasing surface disorder and are essentially temperature--independent. Experimental values of $b$ are approached only when both the coupling of nematic molecules with the substrate and the anisotropy of nematic--nematic interactions are weak.Comment: Revisions primarily in section I

Theory and simulation of the nematic zenithal anchoring coefficient

Combining molecular simulation, Onsager theory and the elastic description of nematic liquid crystals, we study the dependence of the nematic liquid crystal elastic constants and the zenithal surface anchoring coefficient on the value of the bulk order parameter

The Effect of Varying Surface Orientation on the Molecular Organization

We present a Monte Carlo (MC) simulation of a nematic film with boundary conditions that vary from a homogeneous to a homeotropic anchoring at one surface while having a homogeneous anchoring at the other one. The simulations are based on the Lebwohl-Lasher lattice spin model with suitable boundary conditions to mimic the cell. We have investigated temperature effects on the molecular organization inside the system by calculating the internal energy, the heat capacity and the standard nematic order parameter