Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Lattice Dynamics and Melting of a Nonequilibrium Pattern   We present a new description of nonequilibrium square patterns as a
harmonically coupled crystal lattice. In a vertically oscillating granular
layer, different transverse normal modes of the granular square-lattice pattern
are observed for different driving frequencies ($f_d$) and accelerations. The
amplitude of a mode can be further excited by either frequency modulation of
$f_d$ or reduction of friction between the grains and the plate. When the mode
amplitude becomes large, the lattice melts (disorders), in accord with the
Lindemann criterion for melting in two-dimensions.

12
The categories of this paper are: nucl-th
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The categories of this paper are: ao-sci
27
The categories of this paper are: comp-gas
2
The categories of this paper are: math
17
The categories of this paper are: q-fin
23
The categories of this paper are: solv-int
24
The categories of this paper are: dg-ga
15
The categories of this paper are: nucl-ex
1
The categories of this paper are: cs
22
The categories of this paper are: chao-dyn
11
The categories of this paper are: hep-lat
21
The categories of this paper are: adap-org
14
The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc