MONTE-CARLO SIMULATION OF TOPOLOGICAL DEFECTS IN THE NEMATIC LIQUID-CRYSTAL MATRIX AROUND A SPHERICAL COLLOID PARTICLE

We use a Monte Carlo algorithm to simulate the director field around a spherical inclusion in a uniform nematic liquid crystal matrix. The r esulting structure crucially depends on the relative strength of the n ematic bulk elasticity and the director anchoring on the particle surf ace. When this anchoring is weak, the director field perturbations are small and have quadrupolar symmetry. With increasing strength of anch oring two topologically nontrivial situations are possible: a dipolar configuration with a satellite point defect (hedgehog) near the partic le pole, or a quadrupolar configuration with a ''Saturn ring'' of disc lination around the particle equator.