Single-particle spectra of charge transfer insulators

We propose a many-body method for band-structure calculations in strongly correlated electron systems and apply it to NiO. The method may be viewed as a translationally invariant version of the cluster method of Fujimori and Minami, wherein the Coulomb interaction within the d-shells is treated by exact diagonalization and the d-shells then are coupled to a solid by an extension of the cluster perturbation theory (CPT). The method is computationally no more demanding than a conventional band structure calculation and for NiO, we find good agreement between the calculated single-particle spectral function and the experimentally measured band structure. (c) 2005 Elsevier B.V. All rights reserved.