Title: Wigner crystals for a planar, equimolar binary mixture of classical, charged particles
Author(s):

	M. Antlanger (Institut für Theoretische Physik and Center for Computational Materials Science (CMS), Vienna University of Technology, Wiedner Hauptstraße 8-10, A-1040 Wien, Austria; Laboratoire de Physique Théorique (UMR 8627), Université Paris-Sud and CNRS, Bat. 210, F-91405 Orsay Cedex, France)
	G. Kahl (Institut für Theoretische Physik and Center for Computational Materials Science (CMS), Vienna University of Technology, Wiedner Hauptstraße 8-10, A-1040 Wien, Austria)

We have investigated the ground state configurations of an equimolar, binary mixture of classical charged particles (with nominal charges Q₁ and Q₂) that condensate on a neutralizing plane. Using efficient Ewald summation techniques for the calculation of the ground state energies, we have identified the energetically most favorable ordered particle arrangements with the help of a highly reliable optimization tool based on ideas of evolutionary algorithms. Over a large range of charge ratios, q = Q₂ / Q₁, we identify six non-trivial ground states, some of which show a remarkable and unexpected structural complexity. For 0.59 \lesssim q < 1 the system undergoes a phase separation where the two charge species populate in a hexagonal arrangement spatially separated areas.

Key words: Wigner crystals, binary mixture of charged systems, ground states, Ewald summation, evolutionary algorithm
PACS: 52.27.Lw, 64.70.K-, 64.75.St, 73.20.Qt

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