Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Cooperative and non-linear phenomena at the neutral-ionic phase
  transition   The complex interplay among on-site energy, Hubbard U, and coupling to
Holstein and Peierls phonons at the neutral-ionic phase transition is discussed
using diagrammatic valence bond calculations. The charge transfer and
dimerization amplitudes and the infrared intensity of molecular vibrations are
studied in the transition region.

7
The categories of this paper are: hep-th
18
The categories of this paper are: econ
37
The categories of this paper are: supr-con
26
The categories of this paper are: bayes-an
24
The categories of this paper are: dg-ga
27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
3
The categories of this paper are: physics
11
The categories of this paper are: hep-lat
8
The categories of this paper are: hep-ex
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
28
The categories of this paper are: alg-geom