Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electronic structure of the $\rm Ca_3Co_4O_9$ compound from ab initio
  local interactions   We used fully correlated ab initio calculations to determine the effective
parameters of Hubbard and t - J models for the thermoelectric misfit compound
$\rm Ca_3Co_4O_9$. As for the $\rm Na_xCoO_2$ family the Fermi level orbitals
are the $a_{1g}$ orbitals of the cobalt atoms ; the $e'_g$ being always lower
in energy by more than 240\,meV. The electron correlation is found very large
$U/t\sim 26$ as well as the parameters fluctuations as a function of the
structural modulation. The main consequences are a partial $a_{1g}$ electrons
localization and a fluctuation of the in-plane magnetic exchange from AFM to
FM. The behavior of the Seebeck coefficient as a function of temperature is
discussed in view of the ab initio results, as well as the 496\,K phase
transition.

10
The categories of this paper are: q-bio
7
The categories of this paper are: hep-th
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
21
The categories of this paper are: adap-org
17
The categories of this paper are: q-fin
29
The categories of this paper are: funct-an
36
The categories of this paper are: cmp-lg
0
The categories of this paper are: hep-ph
16
The categories of this paper are: stat
26
The categories of this paper are: bayes-an
25
The categories of this paper are: patt-sol
31
The categories of this paper are: ao-sci
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys