title: Topological defects in spherical nematics.
abstract: We study the organization of topological defects in a system of nematogens confined to the two-dimensional sphere (S2). We first perform Monte Carlo simulations of a fluid system of hard rods (spherocylinders) living in the tangent plane of S2. The sphere is adiabatically compressed until we reach a jammed nematic state with maximum packing density. The nematic state exhibits four +1/2 disclinations arrayed on a great circle. This arises from the high elastic anisotropy of the system in which splay (K1) is far softer than bending (K3). We also introduce and study a lattice nematic model on S2 with tunable elastic constants and map out the preferred defect locations as a function of elastic anisotropy. We find a one-parameter family of degenerate ground states in the extreme splay-dominated limit K_{3}/K_{1}-->infinity. Thus the global defect geometry is controllable by tuning the relative splay to bend modulus.
authors.affiliation: Department of Physics, Syracuse University, Syracuse, New York 13244-1130, USA.
authors.forename: Homin
authors.initials: H
authors.lastname: Shin
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Bowick
authors.forename: Xiangjun
authors.initials: X
authors.lastname: Xing