Properties of narrow band insulators
Abstract
The general electronic properties of solids containing narrow bands is explored. A typical example of such a solid at its most difficult is NiO which is insulating, independent of magnetic ordering, and has a narrow, partly filled, 3d Ni band and a broad, filled 2p O band. We approach the description of these solids from a best single determinant point of view and find, for NiO as an example, the O 2p bands best described by conventional energy band theory and the narrow Ni 3d levels by localized states (that is, a valence bond description). Calculations for NiO are performed in this limit using unrestricted Hartree‐Fock techniques. The improvements needed are discussed and systematic techniques for their implementation described. The effect of such improvements is computed for NiO and an electronic structure for NiO is obtained, in reasonable agreement with experiment. Copyright © 1981 John Wiley & Sons, Inc.