Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dynamical transitions and sliding friction in the two-dimensional
  Frenkel-Kontorova model   The nonlinear response of an adsorbed layer on a periodic substrate to an
external force is studied via a two dimensional uniaxial Frenkel-Kontorova
model. The nonequlibrium properties of the model are simulated by Brownian
molecular dynamics. Dynamical phase transitions between pinned solid, sliding
commensurate and incommensurate solids and hysteresis effects are found that
are qualitatively similar to the results for a Lennard-Jones model, thus
demonstrating the universal nature of these features.

3
The categories of this paper are: physics
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
2
The categories of this paper are: math
18
The categories of this paper are: econ
11
The categories of this paper are: hep-lat
5
The categories of this paper are: gr-qc
34
The categories of this paper are: chem-ph
36
The categories of this paper are: cmp-lg
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
0
The categories of this paper are: hep-ph
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th
37
The categories of this paper are: supr-con