Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Challenges for variational reduced-density-matrix theory with
  three-particle N-representability conditions   The direct variational optimization of the two-electron reduced density
matrix (2RDM) can provide a reference-independent description of the electronic
structure of many-electron systems that naturally captures strong or nondynamic
correlation effects. Such variational 2RDM approaches can often provide a
highly accurate description of strong electron correlation, provided that the
2RDMs satisfy at least partial three-particle $N$-representability conditions
({\em e.g.}, the T2 condition). However, recent benchmark calculations on
hydrogen clusters [J. Chem. Phys. {\bf 153}, 104108 (2020)] suggest that even
the T2 condition leads to unacceptably inaccurate results in the case of 2- and
3-dimensional clusters. We demonstrate that these failures persist under the
application of full three-particle $N$-representability conditions (3POS). A
variety of correlation metrics are explored in order to identify regimes under
which 3POS calculations become unreliable, and we find that the relative
squared magnitudes of the cumulant three- and two-particle reduced density
matrices correlates reasonably well with the energy error in these systems.
However, calculations on other molecular systems reveal that this metric is not
a universal indicator for the reliability of reduced-density-matrix theory with
3POS conditions.

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The categories of this paper are: acc-phys
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The categories of this paper are: q-fin
1
The categories of this paper are: cs
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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: plasm-ph
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The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
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The categories of this paper are: econ
30
The categories of this paper are: q-alg
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The categories of this paper are: solv-int
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The categories of this paper are: nlin
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The categories of this paper are: hep-th
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The categories of this paper are: funct-an
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The categories of this paper are: math
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The categories of this paper are: cmp-lg