Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Pair formation in two electron correlated chains   We study two correlated electrons in a nearest neighbour tight- binding
chain, with both on site and nearest neighbour interaction. Both the cases of
parallel and antiparallel spins are considered. In addition to the free
electron band for two electrons, there are correlated bands with positive or
negative energy, depending on wheather the interaction parameters are repulsive
or attractive. Electrons form bound states, with amplitudes that decay
exponentially with separation. Conditions for such states to be filled at low
temperatures are discussed.

34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
17
The categories of this paper are: q-fin
12
The categories of this paper are: nucl-th
37
The categories of this paper are: supr-con
26
The categories of this paper are: bayes-an
5
The categories of this paper are: gr-qc
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga
28
The categories of this paper are: alg-geom
18
The categories of this paper are: econ
36
The categories of this paper are: cmp-lg
1
The categories of this paper are: cs
14
The categories of this paper are: math-ph
15
The categories of this paper are: nucl-ex
7
The categories of this paper are: hep-th