Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Explicitly correlated coupled cluster method for accurate treatment of
  open-shell molecules with hundreds of atoms   We present a near-linear scaling formulation of the explicitly-correlated
coupled-cluster singles and doubles with perturbative triples method
(CCSD(T)$_{\overline{\text{F12}}}$) for high-spin states of open-shell species.
The approach is based on the conventional open-shell CCSD formalism [M. Saitow
et al., J. Chem. Phys. 146, 164105 (2017)] utilizing the domain local
pair-natural orbitals (DLPNO) framework. The use of spin-independent set of
pair-natural orbitals ensures exact agreement with the closed-shell formalism
reported previously, with only marginally impact on the cost (e.g. the
open-shell formalism is only 1.5 times slower than the closed-shell counterpart
for the $\text{C}_\text{160}\text{H}_{\text{322}}$ n-alkane, with the measured
size complexity of $\approx1.2$). Evaluation of coupled-cluster energies near
the complete-basis-set (CBS) limit for open-shell systems with more than 550
atoms and 5000 basis functions is feasible on a single multi-core computer in
less than 3 days. The aug-cc-pVTZ DLPNO-CCSD(T)$_{\overline{\text{F12}}}$
contribution to the heat of formation for the 50 largest molecules among the
348 core combustion species benchmark set [J. Klippenstein et al., J. Phys.
Chem. A 121, 6580 (2017)] had root-mean-square deviation (RMSD) from the
extrapolated CBS CCSD(T) reference values of 0.3 kcal/mol. For a more
challenging set of 50 reactions involving small closed- and open-shell
molecules [G. Knizia et al., J. Chem. Phys. 130, 054104 (2009)] the
aug-cc-pVQ(+d)Z DLPNO-CCSD(T)$_{\overline{\text{F12}}}$ yielded a RMSD of
$\sim$0.4 kcal/mol with respect to the CBS CCSD(T) estimate.

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The categories of this paper are: solv-int
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The categories of this paper are: hep-th
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The categories of this paper are: hep-ex
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The categories of this paper are: cs
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The categories of this paper are: mtrl-th
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The categories of this paper are: math
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The categories of this paper are: q-alg
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The categories of this paper are: atom-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: bayes-an
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The categories of this paper are: patt-sol
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The categories of this paper are: ao-sci
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The categories of this paper are: stat
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The categories of this paper are: math-ph
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The categories of this paper are: quant-ph