Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Structure and electron dynamics of planetary states of Sr below the
  Sr$^+$ $7d$ and $8p$ thresholds   In a combined experimental and theoretical study we investigate the $7dnl$
and $8pnl$ ($n\ge 11$, $l=9-12$) doubly-excited planetary states of Sr. The
experimental spectrum was obtained using a five-photon resonant excitation
scheme. The method of configuration interaction with exterior complex scaling
was used to compute the energy-level structure and dynamics of the two highly
excited electrons from first principles. Good quantitative agreement was
obtained with the spectra we recorded, and the theoretical calculations shed
light on their complex structure and the signatures of electron correlations
therein. The two-electron probability densities we calculated reveal the
strongly-correlated angular motion of the two electrons in the $7dnl$ and
$8pnl$ planetary states, and confirm quantitatively the predictions of the
frozen-planet approximation describing electron dynamics as the polarization of
the fast inner electron by the electric field of the outer "frozen" electron.

10
The categories of this paper are: q-bio
5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin
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The categories of this paper are: nucl-ex
14
The categories of this paper are: math-ph
4
The categories of this paper are: cond-mat
22
The categories of this paper are: chao-dyn
25
The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys