Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Observed Metallization of Hydrogen Interpreted as a Band Structure
  Effect
5
The categories of this paper are: gr-qc
32
The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin
9
The categories of this paper are: nlin
2
The categories of this paper are: math
24
The categories of this paper are: dg-ga
27
The categories of this paper are: comp-gas
26
The categories of this paper are: bayes-an
20
The categories of this paper are: acc-phys
19
The categories of this paper are: eess
30
The categories of this paper are: q-alg
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
8
The categories of this paper are: hep-ex
0
The categories of this paper are: hep-ph