M. Potthoff et al., INFLUENCE OF ELECTRON CORRELATIONS ON AUGER-SPECTRA OF SOLIDS WITH PARTIALLY FILLED BANDS, Journal of electron spectroscopy and related phenomena, 72, 1995, pp. 163-167
We investigate the influence of correlations among the valence-band el
ectrons as well as correlations between valence-band and core electron
s on the Auger line shape of solids. For metals with partially filled
valence bands the relevant many-body problem is no longer exactly solv
able. Usually, approximate solutions are constructed that correctly re
produce different exactly solvable limiting cases. We employ a diagram
matic vertex-correction method (three-particle ladder approximation) t
o calculate the three-particle Green function, which directly yields t
he Auger intensity. The validity of the approximation in limiting case
s is discussed. It turns out that the three-particle ladder approximat
ion gives correct results not only for those cases considered commonly
but also for another limiting case: the limit of strong valence-band-
core interaction. Numerical results for a model system indicate the ap
proximation to be a very reasonable interpolation between the differen
t limits.