https://doi.org/10.1140/epjb/e2010-00063-0
Quantum chemical study of Co3+ spin states in LaCoO3
1
Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Straße 38, 01187 Dresden, Germany
2
Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Russia
3
Physikalische und Theoretische Chemie, Freie Universität Berlin, Takustraße 3, 14195 Berlin, Germany
Corresponding author: siuraksh@jinr.ru
Received:
8
October
2009
Revised:
21
January
2010
Published online:
2
March
2010
Ab initio quantum-chemical cluster calculations are
performed for the perovskite LaCoO3. The main concern is to
calculate the energy level ordering of different spin states of
Co3+, which is an issue of great controversy for many years.
The calculations performed for the trigonal lattice structure at
T = 5 K and 300 K, with the structural data taken from experiment,
display that the low-spin (LS, S = 0) ground state is separated from
the first excited high-spin (HS, S = 2) state by a gap <100 meV,
while the intermediate-spin (IS, S = 1) state is located at much
higher energy ≈0.5 eV. We suggest that the local lattice
relaxation around the Co3+ ion excited to the HS state and the
spin-orbit coupling reduce the spin gap to a value ~10 meV.
Coupling of the IS state to the Jahn-Teller local lattice distortion
is found to be rather strong and reduces its energy position to a
value of 200 300 meV. Details of the quantum-chemical
cluster calculation procedure and the obtained results are
extensively discussed and compared with those reported earlier by
other authors.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2010