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.
Luo
Weidong
W
Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA.
Franceschetti
Alberto
A
Varela
Maria
M
Tao
Jing
J
Pennycook
Stephen J
SJ
Pantelides
Sokrates T
ST