The theoretical study for the perovskite-type manganese fluorides of KMnF3, RbMnF3 and K1-xLixMnF3

We performed the hybrid-density functional theory (DFT) calculations for the strongly correlated perovskite-type manganese fluorides of KMnF3, RbMnF3 and K1-xLixMnF3 In both solids, UBHHLYP, which contains 50% Hartree-Fock exchange term, provided the reasonable effective exchange integral (J(ab)) values, in comparison with the experimental ones. In order to investigate the intrinsic roles of counter cations precisely, we examined the variations of the total energy and J(ab) value, assuming the displacement of counter cation toward < 100 > direction. In KMnF3 (RbMnF3), it was found that the steric repulsion between potassium (rubidium) and bottleneck is large, while that between lithium and bottleneck is negligible in K1-xLixMnF3. Finally, we also showed the possibility of the lithium ion conduction in the antiferromagnetic K1-xLixMnF3. It was concluded that the lithium ion conduction in RMnF3 is possible, if the vacancy at R site exists. (C) 2008 Elsevier Ltd. All rights reserved.