Metal-insulator transition in the two-dimensional fully polarized   homogeneous electron gas from Hartree-Fock solutions
  We determine the ground state of the two-dimensional, fully polarized electron gas within the Hartree-Fock approximation without imposing any particular symmetries on the solutions. At low electronic densities, the Wigner crystal solution is stable, but for higher densities ($r_s$ less than $\sim 3$) we obtain a ground state of different symmetry: the charge density forms a triangular lattice with about 11% more sites than electrons. We argue that this conducting state with broken translational symmetry remains the ground state of the high density region in the thermodynamic limit giving rise to a metal to insulator transition. 
B. Bernu, F. Delyon, M. Duneau, and M. Holzmann