Oxygen-vacancy formation in LaMO3 (M = Ti, V, Cr, Mn, Fe, Co, Ni) calculated at both GGA and GGA plus U levels

The electronic structures of nonmagnetic LaMO3 and LaMO2.875 (M = Ti, V. Cr, Mn, Fe, Co, Ni) have been calculated within both the standard GGA and the GGA + U frameworks, and the corresponding energetics for oxygen-vacancy formation were evaluated. The oxygen-vacancy formation modifies the positions of the atoms beyond the nearest neighbors, donating electrons mainly to the adjacent M atoms. However, the extent of the donation localization varies with the M species, changing the displacement directions of the adjacent M atoms. Such findings can be understood on the basis of the electronic structures, and roughly correlated with the 3rd ionization energies of M and La, signaling the validation of the ionic models in the present species. The vacancy formation energy evaluated at both computational levels generally decreases with the increasing M atomic number. (c) 2011 Elsevier B.V. All rights reserved.