Influence of parameters U and J in the LSDA+U method on electronic structure of the perovskites LaMO3 (M = Cr,Mn,Fe,Co,Ni)

The electronic structures of the perovskite oxides LaMO3 (M = Cr, Mn, Fe, C o, and Ni) have been studied in the local-spin density approximation LSDA U method with the on-site Coulomb interaction parameter U varying from 0.0 to 10.5 eV, and exchange parameter J, from 0.35 to 0.95 eV. It is found th at the splitting of the occupied spin-up bands and the corresponding unoccu pied spin-down bands increases almost linearly with the increase of U, whil e the positions of the completely empty orbitals (both spin-up and -down ba nds are unoccupied) are not sensitive to the value of U. These features cau se the gaps of the compounds to increase first with U, and then they can in crease (LaFeO3), decrease (LaCrO3 and LaMnO3) or even drop to zero (LaCoO3) . The local magnetic moments increase linearly with increasing U. After con sidering the on-site Coulomb interaction, the binding energies for the pero vskites are lowered, and decrease with the increase of U. The exchange para meter J also influences the electronic properties, though not as strongly a s that of the U. A group of values of U and J parameters, which can give re sults closer to that given by experiments; have been found. [S0163-1829(99) 00144-7].