Simulations of Helix Unwinding in Ferroelectric Liquid Crystals

TL;DR

This paper presents a mesoscale simulation model to study helix unwinding in ferroelectric liquid crystals, revealing how boundary effects and electric fields influence the unwinding process and polarization, aligning with experimental observations.

Contribution

Develops a continuum free energy-based simulation model to analyze helix unwinding in ferroelectric liquid crystals considering boundary effects and electric fields.

Findings

Boundary effects lower the critical unwinding field.

Cell size influences saturation polarization.

Simulation results match experimental data.

Abstract

In bulk ferroelectric liquid crystals, the molecular director twists in a helix. In narrow cells, this helix can be unwound by an applied electric field or by boundary effects. To describe helix unwinding as a function of both electric field and boundary effects, we develop a mesoscale simulation model based on a continuum free energy discretized on a two-dimensional lattice. In these simulations, we determine both the director profile across the cell and the net electrostatic polarization. By varying the cell size, we show how boundary effects shift the critical field for helix unwinding and lower the saturation polarization. Our results are consistent with experimental data.