Orientational order and defect structures on curved surfaces*

We study the topological defects in a nematic liquid crystal confined to a surface. Using Monte Carlo simulations, we investigate how the position and number of defects depend on the interaction strength, the shape of the surface and other physical parameters. On a spherical surface, we find that the interaction changes the location of four +1/2 defects initially sitting on a great circle of the sphere to the vertices of a tetrahedron. In deformed spheres, we observe the coalescence of defects into two single +1 defects.