The many faces of topological defects in smectic liquid crystals

Liquid crystal structures in confined space inevitably feature topological defects through the requirements set by the boundary conditions. The Euler characteristic of the shape of the cavity imposes the total contained topological charge.

As previous work has largely focused on understanding the topological defects in nematic liquid crystals, our goal is to quantify the topological features of smectic states in confinement. For these high-density states the enhanced rigidity suppresses elastic deformations in favour of disclination lines at which the orientations of the fluid molecules is discontinuous.

We use canonical Monte Carlo simulations for a model fluid of hard spherocylinders in two dimensions to generate smectic-A liquid crystal states in a range of polygonal cavities. With the help of the particle-resolved snapshots and extracted orientational distributions, we determine the shape and topology of the emerging networks of disclination lines.