Computer simulation of topological defects around a colloidal particle or droplet dispersed in a nematic host - art. no. 041701

We use molecular dynamics to study the ordering of a nematic liquid crystal around a spherical particle or droplet. Homeotropic boundary conditions an d strong anchoring create a hedgehog (radial point defect) director configu ration on the particle surface and in its vicinity: this topological defect is canceled by nearby defect structures in the surrounding liquid crystal, so as to give a uniform director field at large distances. We observe thre e defect structures for different particle sizes: a quadrupolar one with a ring defect surrounding the particle in the equatorial plane; a dipolar one with a satellite defect at the north or south pole; and a transitional, no nequatorial, ring defect. These observations are broadly consistent with th e predictions of the simplest elastic theory. By studying density and order -parameter maps, we are able to examine behavior near the particle surface, and in the disclination core region, where the elastic theory is inapplica ble. Despite the relatively small scale of the inhomogeneities in our syste ms, the simple theory gives reasonably accurate predictions of the variatio n of defect position with particle size.