Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Dynamics of classical and quantum spin in external fields: A general
  formalism
36
The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
17
The categories of this paper are: q-fin
32
The categories of this paper are: atom-ph
1
The categories of this paper are: cs
2
The categories of this paper are: math
26
The categories of this paper are: bayes-an
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
16
The categories of this paper are: stat
34
The categories of this paper are: chem-ph