Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the atomic orbital magnetism: A rigorous derivation of the Larmor and
  Van Vleck contributions   The purpose of this paper is to rigorously investigate the orbital magnetism
of core electrons in 3-dimensional crystalline ordered solids and in the
zero-temperature regime. To achieve that, we consider a non-interacting Fermi
gas subjected to an external periodic potential modeling the crystalline field
within the tight-binding approximation (i.e. when the distance between two
consecutive ions is large). For a fixed number of particles in the Wigner-Seitz
cell and in the zero-temperature limit, we derive an asymptotic expansion for
the bulk zero-field orbital susceptibility. We prove that the leading term is
the superposition of the Larmor diamagnetic contribution, generated by the
quadratic part of the Zeeman Hamiltonian, together with the 'complete' orbital
Van Vleck paramagnetic contribution, generated by the linear part of the Zeeman
Hamiltonian, and related to field-induced electronic transitions.

6
The categories of this paper are: astro-ph
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
25
The categories of this paper are: patt-sol
7
The categories of this paper are: hep-th
15
The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
18
The categories of this paper are: econ
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
29
The categories of this paper are: funct-an
36
The categories of this paper are: cmp-lg
16
The categories of this paper are: stat
20
The categories of this paper are: acc-phys
35
The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th