Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The generalized Kadanoff-Baym ansatz. Computing nonlinear response
  properties of finite systems   For a minimal Hubbard-type system at different interaction strengths U, we
investigate the density-response for an excitation beyond the linear regime
using the generalized Kadanoff-Baym ansatz (GKBA) and the second Born (2B)
approximation. We find strong correlation features in the response spectra and
establish the connection to an involved double excitation process. By comparing
approximate and exact Green's function results, we also observe an anomalous
U-dependence of the energy of this double excitation in 2B+GKBA. This is in
accordance with earlier findings [K. Balzer et al., EPL 98, 67002 (2012)] on
double excitations in quantum wells.

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The categories of this paper are: dg-ga
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The categories of this paper are: quant-ph
36
The categories of this paper are: cmp-lg
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The categories of this paper are: q-fin
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The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
34
The categories of this paper are: chem-ph
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The categories of this paper are: adap-org
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The categories of this paper are: q-bio
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The categories of this paper are: nucl-th
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The categories of this paper are: chao-dyn
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The categories of this paper are: alg-geom
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The categories of this paper are: mtrl-th
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The categories of this paper are: bayes-an
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The categories of this paper are: eess
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The categories of this paper are: hep-lat