Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Mountaineering Strategy to Excited States: Revising Reference Values
  with EOM-CC4   In the framework of the computational determination of highly-accurate
vertical excitation energies in small organic compounds, we explore the
possibilities offered by the equation-of-motion formalism relying on the
approximate fourth-order coupled-cluster (CC) method, CC4. We demonstrate,
using an extended set of more than 200 reference values based on CC including
up to quadruples excitations (CCSDTQ), that CC4 is an excellent approximation
to CCSDTQ for excited states with a dominant contribution from single
excitations with an average deviation as small as $0.003$ eV. We next assess
the accuracy of several additive basis set correction schemes, in which
vertical excitation energies obtained with a compact basis set and a high-order
CC method are corrected with lower-order CC calculations performed in larger
basis sets. Such strategies are found to be overall very beneficial, though
their accuracy depend significantly on the actual scheme. Finally, CC4 is
employed to improve several theoretical best estimates of the QUEST database
for molecules containing between four and six (non-hydrogen) atoms, for which
previous estimates were computed at the CCSDT level.

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The categories of this paper are: bayes-an
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The categories of this paper are: adap-org
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The categories of this paper are: cmp-lg
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The categories of this paper are: chao-dyn
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The categories of this paper are: eess
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The categories of this paper are: hep-ex
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The categories of this paper are: q-fin
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The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: patt-sol
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The categories of this paper are: plasm-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: solv-int
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The categories of this paper are: cs
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The categories of this paper are: math-ph