Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Covalency, double-counting and the metal-insulator phase diagram in
  transition metal oxides   Dynamical mean field theory calculations are used to show that for late
transition-metal-oxides a critical variable for the Mott/charge-transfer
transition is the number of d-electrons, which is determined by charge transfer
from oxygen ions. Insulating behavior is found only for a narrow range of
d-occupancy, irrespective of the size of the intra-d Coulomb repulsion. The
result is useful in interpreting 'density functional +U' and 'density
functional plus dynamical mean field' methods in which additional correlations
are applied to a specific set of orbitals and an important role is played by
the 'double counting correction' which dictates the occupancy of these
correlated orbitals. General considerations are presented and are illustrated
by calculations for two representative transition metal oxide systems: layered
perovskite Cu-based "high-Tc" materials, an orbitally non-degenerate
electronically quasi-two dimensional systems, and pseudocubic rare earch
nickelates, an orbitally degenerate electronically three dimensional system.
Density functional calculations yield d-occupancies very far from the Mott
metal-insulator phase boundary in the nickelate materials, but closer to it in
the cuprates, indicating the sensitivity of theoretical models of the cuprates
to the choice of double counting correction and corroborating the critical role
of lattice distortions in attaining the experimentally observed insulating
phase in the nickelates.

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The categories of this paper are: acc-phys
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The categories of this paper are: hep-ex
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The categories of this paper are: hep-lat
3
The categories of this paper are: physics
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The categories of this paper are: plasm-ph
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The categories of this paper are: adap-org
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The categories of this paper are: supr-con
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The categories of this paper are: q-alg
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The categories of this paper are: hep-th
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The categories of this paper are: chao-dyn
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The categories of this paper are: quant-ph
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The categories of this paper are: math
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The categories of this paper are: cs
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The categories of this paper are: q-bio
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The categories of this paper are: solv-int
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The categories of this paper are: alg-geom