Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum Theory of Orbital Magnetization and its Generalization to
  Interacting Systems   Based on standard perturbation theory, we present a full quantum derivation
of the formula for the orbital magnetization in periodic systems. The
derivation is generally valid for insulators with or without a Chern number,
for metals at zero or finite temperatures, and at weak as well as strong
magnetic fields. The formula is shown to be valid in the presence of
electron-electron interaction, provided the one-electron energies and wave
functions are calculated self-consistently within the framework of the exact
current and spin density functional theory.

2
The categories of this paper are: math
27
The categories of this paper are: comp-gas
34
The categories of this paper are: chem-ph
31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th
32
The categories of this paper are: atom-ph
30
The categories of this paper are: q-alg
18
The categories of this paper are: econ
0
The categories of this paper are: hep-ph
13
The categories of this paper are: quant-ph
5
The categories of this paper are: gr-qc
3
The categories of this paper are: physics
17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
23
The categories of this paper are: solv-int