Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Molecular dynamics study of a classical two-dimensional electron system:
  Positional and orientational orders   Molecular dynamics simulation is used to investigate the crystallization of a
classical two-dimensional electron system, in which electrons interact with the
Coulomb repulsion. From the positional and the orientational correlation
functions, we have found an indication that the solid phase has a
quasi-long-range (power-law correlated) positional order and a long-range
orientational order. This implies that the long-range 1/r system shares the
absence of the true long-range crystalline order at finite temperatures with
short-range ones for which Mermin's theorem applies. We also discuss the
existence of the ``hexatic'' phase predicted by the
Kosterlitz-Thouless-Halperin-Nelson-Young theory.

14
The categories of this paper are: math-ph
12
The categories of this paper are: nucl-th
30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
29
The categories of this paper are: funct-an
0
The categories of this paper are: hep-ph
19
The categories of this paper are: eess
32
The categories of this paper are: atom-ph
2
The categories of this paper are: math
3
The categories of this paper are: physics
27
The categories of this paper are: comp-gas
25
The categories of this paper are: patt-sol