Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetic Interactions in Relativistic Two Particle Systems   The magnetic interactions of the two electrons in helium-like ions are
studied in detail within the framework of Relativistic Schroedinger Theory
(RST). The general results are used to compute the ground-state interaction
energy of some highly-ionized atoms ranging from germanium (Z=32) up to bismuth
(Z=83). When the magnetic interaction energy is added to its electric
counterpart resulting from the electrostatic approximation, the present RST
predictions reach a similar degree of precision (relative to the experimental
data) as the other theoretical approaches known in the literature. However
since the RST magnetism is then treated only in lowest-order approximation,
further improvements of the RST predictions seem possible.

15
The categories of this paper are: nucl-ex
36
The categories of this paper are: cmp-lg
28
The categories of this paper are: alg-geom
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th
21
The categories of this paper are: adap-org
23
The categories of this paper are: solv-int
18
The categories of this paper are: econ
20
The categories of this paper are: acc-phys
34
The categories of this paper are: chem-ph
4
The categories of this paper are: cond-mat
26
The categories of this paper are: bayes-an
35
The categories of this paper are: mtrl-th
6
The categories of this paper are: astro-ph
8
The categories of this paper are: hep-ex
33
The categories of this paper are: plasm-ph