Liquid crystal director fluctuations and surface anchoring by molecular simulation

Abstract

We propose a simple and reliable method to measure the liquid crystal surface anchoring strength by molecular simulation. The method is based on the measurement of the long-range fluctuation modes of the director in confined geometry. As an example, molecular simulations of a liquid crystal in slab geometry between parallel walls with homeotropic anchoring have been carried out using the Monte Carlo technique. By studying different slab thicknesses, we are able to calculate separately the position of the elastic boundary condition, and the extrapolation length.

Colloidal particles in liquid crystal films and at interfaces

“…It has been used to simulate various bulk properties of liquid crystals, such as bulk elastic constants [10][11][12][13][14][15][16], viscosities [17,18], helical twisting power [19,20], parameters of the isotropicnematic interface [21]. Moreover, recent works have also proved that computer simulations can be effectively applied to the study of confined geometries [22,23].…”

Spatial Order in Liquid Crystals: Computer Simulations of Systems of Ellipsoids

“…These are of great interest in the liquid crystal display technology [91]. Therefore, a growing number of simulations are devoted to the study of model nematics at surfaces [93,94,95,96,97,98,99,100,101,102,103,104,105,106,107]. and interfaces [108,109,110,111,112] or in thin films [24,25,113,114,115,116,117,118].…”

“…Obtaining the anchoring energy is more difficult and time consuming. Allen and coworkers have devised different methods and applied them to systems of ellipsoids at hard, planar walls [106,107]. The interfacial tension can be computed from the anisotropy of the pressure tensor close to the surface [111,119], or in the case of fluid-fluid interfaces from their undulations (capillary waves) [112].…”

Monte Carlo simulations of liquid crystals near rough walls

“…q z is a wave vector with a discrete spectrum 19 , χ = q z L e , and κ = k z L e . ζ is the anchoring strength parameter…”

“…The surface anchoring coefficient is determined by the director fluctuation method 19,20 . This method relates thermal director fluctuations in a confined geometry to the zenithal anchoring coefficient, in a similar manner as the fluctuations in a bulk LC can be related to the bulk elastic constants 21,22 .…”