Abstract
We consider the case of narrow, almost filled valence-band solids and present a method for an ab initio description of correlation and disorder effects in the one-particle spectrum as seen in photoemission. For filled (empty) bands, we also consider the two-body propagator, which enters the theoretical formulation of Auger emission. In order to deal with the late transition metals and their alloys: (i) we consider the case of an almost filled band, homogeneous solid, with band degeneracy, Coulomb and spin-orbit interactions; after deriving a k-dependent self-energy in the T-matrix approximation, we recover its local, nondispersive limit, to be used in the nonhomogeneous case; and (ii) for the case of substitutional disorder, we introduce a minimal-size supercell approach in which correlation effects are treated by a local self-energy as calculated in (i) and disorder is included by a constrained determination of the supercell configuration. The method and its significance for realistic ab initio calculations of correlated, disordered alloys are illustrated in terms of a single band, disordered Hubbard Hamiltonian. Model results for the one- and two-body spectra are shown and discussed.
DOI:https://doi.org/10.1103/PhysRevB.55.16143
©1997 American Physical Society