Dynamical Heterogeneities and Cooperative Motion in Smectic Liquid Crystals

TL;DR

This study uses simulations to reveal non-Gaussian diffusion, heterogeneous dynamics, and cooperative stringlike clusters in smectic liquid crystals, highlighting similarities to supercooled liquids despite their equilibrium nature.

Contribution

It uncovers the presence of non-Gaussian diffusion, permanent barriers, and cooperative motion in smectic liquid crystals, linking their dynamics to those of supercooled liquids.

Findings

Non-Gaussian diffusion observed in smectic phases

Presence of permanent barriers for layer-to-layer diffusion

Detection of stringlike cooperative clusters of rods

Abstract

Using simulations of hard rods in smectic-A states, we find non-gaussian diffusion and heterogeneous dynamics due to the equilibrium periodic smectic density profiles, which give rise to permanent barriers for layer-to-layer diffusion. This relaxation behavior is surprisingly similar to that of non-equilibrium supercooled liquids, although there the particles are trapped in transient (instead of permanent) cages. Interestingly, we also find stringlike clusters of up to 10 inter-layer rods exhibiting dynamic cooperativity in this equilibrium state.