Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Antiferromagnetism in the 2D Hubbard model: phase transition and local
  quantities   We present a first study of the antiferromagnetic state in the 2D t-t'-U
model at finite temperatures by the composite operator method, providing
simultaneously a fully self-consistent treatment of the paramagnetic and the AF
phase. Near half-filling the critical value of the Coulomb repulsion as a
function of t' and the temperature dependence of the magnetization and of the
internal energy per site have been studied.

33
The categories of this paper are: plasm-ph
8
The categories of this paper are: hep-ex
6
The categories of this paper are: astro-ph
7
The categories of this paper are: hep-th
16
The categories of this paper are: stat
23
The categories of this paper are: solv-int
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
32
The categories of this paper are: atom-ph
25
The categories of this paper are: patt-sol
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con