DIRECTOR STRUCTURE AROUND A COLLOID PARTICLE SUSPENDED IN A NEMATIC LIQUID-CRYSTAL

We analyze the director field around a spherical colloid particle with radial (homeotropic) anchoring on its surface. Depending on the relat ive strength of anchoring W, controlled by the parameter WR/K with K t he Frank constant and R the particle radius, the director distribution may possess a singular ring of a -1/2 disclination the equatorial pla ne. The equilibrium radius of this ring, at rigid radial anchoring, is aapproximate to 1.25R and only weakly depends on the disclination co re energy. At small anchoring the director field is regular and weakly disturbed by the particle, there is a characteristic crossover W bet ween thr two regimes. We obtain tile analytical expression for n(r), w hich decays as r(-3) sin 2 theta away from the particle, and compare i t with the exact numerical solution in the highly distorted nonlinear regime.