Relaxation of a supercooled low-density Coulomb fluid

A system of charged hard spheres in front of a homogeneous neutralizing background is studied at low densities using mode-coupling theory. A “Wigner glass” phase, the amorphous analog of the Wigner crystal recently found in experiments, is predicted. The melting curve of the Wigner glass obeys $n\propto T^3$, and the particle localization length is much larger than the Lindemann criterion would predict. An analysis of transport properties shows that huge effective particle diameters are responsible for the glassification at low densities. The Stokes-Einstein relation, which is obeyed by the high-density fluid, implies large Stokes radii at low densities.