Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Density-functional theory of inhomogeneous electron systems in thin
  quantum wires
10
The categories of this paper are: q-bio
13
The categories of this paper are: quant-ph
18
The categories of this paper are: econ
24
The categories of this paper are: dg-ga
26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
6
The categories of this paper are: astro-ph
32
The categories of this paper are: atom-ph
2
The categories of this paper are: math
3
The categories of this paper are: physics
37
The categories of this paper are: supr-con
5
The categories of this paper are: gr-qc
1
The categories of this paper are: cs
19
The categories of this paper are: eess
16
The categories of this paper are: stat