Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Beyond Nonlinear Schr\"odinger Equation Approximation for an Anharmonic
  Chain with Harmonic Long Range Interaction   Multi scales method is used to analyze a nonlinear differential-difference
equation. In order $\epsilon^3$ the NLS equation is found to determine the
space-time evolution of the leading amplitude. In the next order this has to
satisfy a complex mKdV equation (the next in the NLS hierarchy) in order to
eliminate secular terms. The zero dispersion point case is also analyzed and
the relevant equation is a modified NLS equation with a third order derivative
term included

12
The categories of this paper are: nucl-th
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc
18
The categories of this paper are: econ
36
The categories of this paper are: cmp-lg
8
The categories of this paper are: hep-ex
27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
10
The categories of this paper are: q-bio
32
The categories of this paper are: atom-ph
33
The categories of this paper are: plasm-ph
26
The categories of this paper are: bayes-an
3
The categories of this paper are: physics
14
The categories of this paper are: math-ph