Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Accuracy of the Faddeev Random Phase Approximation for Light Atoms   The accuracy of the Faddeev random phase approximation (FRPA) method is
tested by calculating the total and ionization energies of a set of light atoms
up to Ar. Comparisons are made with the results of coupled-cluster singles and
doubles (CCSD), third-order algebraic diagrammatic construction [ADC(3)], and
with the experiment. It is seen that even for two-electron systems, He and
Be-2+, the inclusion of RPA effects leads to satisfactory results and therefore
it does not over-correlate the ground state. The FRPA becomes progressively
better for larger atomic numbers where it gives about 5 mH more correlation
energy and it shifts ionization potentials by 2-10 mH, with respect to its
sister method ADC(3). The corrections for ionization potentials consistently
reduce the discrepancies with the experiment.

36
The categories of this paper are: cmp-lg
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
4
The categories of this paper are: cond-mat
11
The categories of this paper are: hep-lat
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
6
The categories of this paper are: astro-ph
24
The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
5
The categories of this paper are: gr-qc
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs