We investigate Thomson's problem of charges on a sphere as an example
of a system with complex interactions. Assuming certain symmetries we
can work with a larger number of charges than before. We found that, w
hen the number of charges is large enough, the lowest energy states ar
e not those with the highest symmetry. As predicted previously by Dodg
son and Moore, the complex patterns in these states involve dislocatio
n defects which screen the strains of the 12 disclinations required to
satisfy Euler's theorem.