Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Two-time Green function method in quantum electrodynamics of high-Z
  few-electron atoms   The two-time Green function method in quantum electrodynamics of high-Z
few-electron atoms is described in detail. This method provides a simple
procedure for deriving formulas for the energy shift of a single level and for
the energies and wave functions of degenerate and quasi-degenerate states. It
also allows one to derive formulas for the transition and scattering
amplitudes. Application of the method to resonance scattering processes yields
a systematic theory for the spectral line shape. The practical ability of the
method is demonstrated by deriving formulas for the QED and
interelectronic-interaction corrections to energy levels and transition and
scattering amplitudes in one-, two-, and three-electron atoms. Numerical
calculations of the Lamb shift, the hyperfine splitting, the bound-electron g
factor, and the radiative recombination cross section in heavy ions are also
reviewed.

6
The categories of this paper are: astro-ph
17
The categories of this paper are: q-fin
26
The categories of this paper are: bayes-an
20
The categories of this paper are: acc-phys
34
The categories of this paper are: chem-ph
30
The categories of this paper are: q-alg
10
The categories of this paper are: q-bio
25
The categories of this paper are: patt-sol
21
The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
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The categories of this paper are: hep-ex
4
The categories of this paper are: cond-mat
36
The categories of this paper are: cmp-lg
0
The categories of this paper are: hep-ph
27
The categories of this paper are: comp-gas
32
The categories of this paper are: atom-ph