Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Ab initio calculations of ultra-short carrier dynamics in 2D materials:
  valley depolarization in single-layer WSe$_2$
20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
28
The categories of this paper are: alg-geom
2
The categories of this paper are: math
8
The categories of this paper are: hep-ex
3
The categories of this paper are: physics
29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
36
The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
16
The categories of this paper are: stat