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MM: Fachverband Metall- und Materialphysik

MM 26: Electronic properties III

MM 26.2: Talk

Wednesday, March 28, 2007, 17:00–17:15, H6

topolgical defects in the crystalline state of the non-uniform density one component plasma — •adil mughal and mike moore — department of physics and astronomy, university of manchester, manchester, m13 9pl, u.k.

We study the ground state properties of classical Coulomb charges moving on a plane but confined either by a circular hard wall boundary or by a harmonic potential. The charge density in the continuum limit is determined analytically and is non-uniform. Because of the non-uniform density there are both disclinations and dislocations present and their distribution across the system is calculated and shown to be in agreement with numerical studies of systems of N charges, where values of N up to 5000 have been studied. A consequence of these defects is that although the charges locally form into a triangular lattice structure, the lattice lines acquire a marked curvature. A study is made of conformal crystals to illuminate the origin of this curvature. The scaling of various terms which contribute to the overall energy of the system of charges viz, the continuum electrostatic energy, correlation energy, surface energy (and so on) as a function of the number of particles N is determined. ``Magic number'' clusters are those at special values of N whose energies take them below the energy estimated from the scaling forms and are identified with charge arrangements of high symmetry.