Forces between elongated particles in a nematic colloid

TL;DR

This study uses molecular dynamics simulations and elastic free energy calculations to analyze the interactions between elongated colloidal particles in a nematic liquid crystal, revealing nonlinear effects and defect dynamics.

Contribution

It provides new insights into the elastic interactions and defect behavior of elongated colloids in nematic hosts, highlighting differences from classical quadrupolar models.

Findings

Depletion forces dominate the interactions.

Elastic contributions differ from quadrupolar predictions.

Nonlinear effects influence defect structures at small separations.

Abstract

Using molecular dynamics (MD) simulations we study the interactions between elongated colloidal particles (length to breath ratio > 1) in a nematic host. The simulation results are compared to the results of a Landau-de Gennes elastic free energy. We find that depletion forces dominate for the sizes of the colloidal particles studied. The tangential component of the force, however, allows us to resolve the elastic contribution to the total interaction. We find that this contribution differs from the quadrupolar interaction predicted at large separations. The difference is due to the presence of nonlinear effects, namely th e change in the positions and structure of the defects and their annihilation at small separations.