Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Nitrogen defects and ferromagnetism of Cr-doped AlN diluted magnetic
  semiconductor from first principles
6
The categories of this paper are: astro-ph
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
11
The categories of this paper are: hep-lat
25
The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
17
The categories of this paper are: q-fin
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an
3
The categories of this paper are: physics
37
The categories of this paper are: supr-con