Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Topological Defects and Non-homogeneous Melting of Large 2D Coulomb
  Clusters   The configurational and melting properties of large two-dimensional clusters
of charged classical particles interacting with each other via the Coulomb
potential are investigated through the Monte Carlo simulation technique. The
particles are confined by a harmonic potential. For a large number of particles
in the cluster (N>150) the configuration is determined by two competing
effects, namely in the center a hexagonal lattice is formed, which is the
groundstate for an infinite 2D system, and the confinement which imposes its
circular symmetry on the outer edge. As a result a hexagonal Wigner lattice is
formed in the central area while at the border of the cluster the particles are
arranged in rings. In the transition region defects appear as dislocations and
disclinations at the six corners of the hexagonal-shaped inner domain. Many
different arrangements and type of defects are possible as metastable
configurations with a slightly higher energy. The particles motion is found to
be strongly related to the topological structure. Our results clearly show that
the melting of the clusters starts near the geometry induced defects, and that
three different melting temperatures can be defined corresponding to the
melting of different regions in the cluster.

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The categories of this paper are: gr-qc
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The categories of this paper are: q-fin
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The categories of this paper are: hep-lat
27
The categories of this paper are: comp-gas
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The categories of this paper are: eess
34
The categories of this paper are: chem-ph
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
28
The categories of this paper are: alg-geom
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The categories of this paper are: cs
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The categories of this paper are: hep-th
23
The categories of this paper are: solv-int
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The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org
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The categories of this paper are: econ
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The categories of this paper are: acc-phys