Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Stretched or noded orbital densities and self-interaction correction in
  density functional theory   Semi-local approximations to the density functional for the
exchange-correlation energy of a many-electron system necessarily fail for
lobed one-electron densities, including not only the familiar stretched
densities but also the less familiar but closely-related noded ones. The
Perdew-Zunger (PZ) self-interaction correction (SIC) to a semi-local
approximation makes that approximation exact for all one-electron ground- or
excited-state densities and accurate for stretched bonds. When the minimization
of the PZ total energy is made over real localized orbitals, the orbital
densities can be noded, leading to energy errors in many-electron systems.
Minimization over complex localized orbitals yields nodeless orbital densities,
which reduce but typically do not eliminate the SIC errors of atomization
energies. Other errors of PZ SIC remain, attributable to the loss of the exact
constraints and appropriate norms that the semi-local approximations satisfy,
and suggesting the need for a generalized SIC. These conclusions are supported
by calculations for one-electron densities, and for many-electron molecules.
While PZ SIC raises and improves the energy barriers of standard generalized
gradient approximations (GGA's) and meta-GGA's, it reduces and often worsens
the atomization energies of molecules. Thus PZ SIC raises the energy more as
the nodality of the valence localized orbitals increases from atoms to
molecules to transition states. PZ SIC is applied here in particular to the
SCAN meta-GGA, for which the correlation part is already self-interaction-free.
That property makes SCAN a natural first candidate for a generalized SIC.

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The categories of this paper are: nlin
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The categories of this paper are: solv-int
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The categories of this paper are: astro-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: econ
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The categories of this paper are: stat
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The categories of this paper are: nucl-th
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The categories of this paper are: acc-phys
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The categories of this paper are: hep-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: cmp-lg
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The categories of this paper are: cs
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The categories of this paper are: hep-th
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The categories of this paper are: q-alg
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The categories of this paper are: alg-geom
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The categories of this paper are: funct-an