Orbital-occupancy versus charge ordering and the strength of electron correlations in electron-doped CaMnO3.
The structural, electronic, and magnetic properties of mixed-valence compounds are believed to be governed by strong electron correlations. Here we report benchmark density-functional calculations in the spin-polarized generalized-gradient approximation (GGA) for the ground-state properties of doped CaMnO(3). We find excellent agreement with all available data, while inclusion of strong correlations in the GGA+U scheme impairs this agreement. We demonstrate that formal oxidation states reflect only orbital occupancies, not charge transfer, and resolve outstanding controversies about charge ordering.
Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA.
Weidong
W
Luo
Alberto
A
Franceschetti
Maria
M
Varela
Jing
J
Tao
Stephen J
SJ
Pennycook
Sokrates T
ST
Pantelides