Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Revisiting the variational two-particle reduced density matrix for
  nuclear systems   In most nuclear many-body methods, observables are calculated using many-body
wave functions explicitly. The variational two-particle reduced density matrix
method is one of the few exceptions to the rule. Ground-state energies of both
closed-shell and open-shell nuclear systems can indeed be evaluated by
minimizing a constrained linear functional of the two-particle reduced density
matrix. However, it has virtually never been used in nuclear theory, because
nuclear ground states were found to be well overbound, contrary to those of
atoms and molecules. Consequently, we introduced new constraints in the nuclear
variational two-particle reduced density matrix method, developed recently for
atomic and molecular systems. Our calculations then show that this approach can
provide a proper description of nuclear systems where only valence neutrons are
included. For the nuclear systems where both neutrons and protons are active,
however, the energies obtained with the variational two-particle reduced
density matrix method are still overbound. The possible reasons for the noticed
discrepancies and solutions to this problem will be discussed.

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The categories of this paper are: atom-ph
25
The categories of this paper are: patt-sol
17
The categories of this paper are: q-fin
16
The categories of this paper are: stat
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The categories of this paper are: ao-sci
28
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: comp-gas
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The categories of this paper are: cmp-lg
4
The categories of this paper are: cond-mat
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The categories of this paper are: dg-ga
7
The categories of this paper are: hep-th
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The categories of this paper are: bayes-an
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The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph