Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Photoionization of negatively charged NV centers in diamond: theory and
  ab initio calculations
25
The categories of this paper are: patt-sol
33
The categories of this paper are: plasm-ph
1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
11
The categories of this paper are: hep-lat
20
The categories of this paper are: acc-phys
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
24
The categories of this paper are: dg-ga
28
The categories of this paper are: alg-geom
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph
7
The categories of this paper are: hep-th
26
The categories of this paper are: bayes-an
29
The categories of this paper are: funct-an