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

TL;DR

This study uses Monte Carlo simulations to analyze external and intrinsic anchoring effects in nematic liquid crystals, revealing how surface disorder and interaction anisotropy influence anchoring strength and extrapolation length.

Contribution

It provides the first detailed Monte Carlo analysis of both external and intrinsic anchoring in nematic liquid crystals with disordered substrates.

Findings

Extrapolation length increases with surface disorder.

Extrapolation length is temperature-independent.

Experimental values are approached with weak substrate coupling and anisotropy.

Abstract

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.