Antiferromagnetism and the band gap in d-metal oxides in the local spin density approximation: NiO and La2CuO4

Abstract

The failure of the local density approximation (LDA) for the description of the electronic structure narrow-band transition metal oxides is discussed. It has been shown that the self-interaction correction (SIC) method improves the value of the bandgap, but can distort the valence states distribution. We propose the “prescription” of the potential construction which corrects only the potentials acting upon the electrons in vacant states and leaves unchanged the potential for occupied states. The use of this correction in the self-consistent LDA electronic structure calculation of NiO not only gave the correct value of the bandgap, ∼4 eV, but also significantly improved the value of the magnetic moment on nickel. It has been shown that the magnetic moment on nickel exists independently of the magnetic order type, that corroborates the localized nature of magnitude moments in NiO. By contrast with the usual LDA calculations, which lead to the nonmagnetic metallic ground state for La2CuO4, self-consistent LDA calculations with the corrections suggested by the present authors gave stable antiferromagnetic solutions with a copper magnetic moment value 0.38μB and a semiconductor type of electronic structure with bandgap value of 0.78 eV.