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Three-Body and One-Body Channels of the Auger Core-Valence-Valence decay: Simplified Approach

A. Marini·M. Cini
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Abstract

We propose a computationally simple model of Auger and APECS line shapes from open-band solids. Part of the intensity comes from the decay of unscreened core-holes and is obtained by the two-body Green's function $G^{(2)}_ω$, as in the case of filled bands. The rest of the intensity arises from screened core-holes and is derived using a variational description of the relaxed ground state; this involves the two-holes-one-electron propagator $G_ω$, which also contains one-hole contributions. For many transition metals, the two-hole Green's function $G^{(2)}_ω$ can be well described by the Ladder Approximation, but the three-body Green's function poses serious further problems. To calculate $G_ω$, treating electrons and holes on equal footing, we propose a practical approach to sum the series to all orders. We achieve that by formally rewriting the problem in terms of a fictitious three-body interaction. Our method grants non-negative densities of states, explains the apparent negative-U behavior of the spectra of early transition metals and interpolates well between weak and strong coupling, as we demonstrate by test model calculations.

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A. Marini, M. Cini. 1999-06-10. Three-Body and One-Body Channels of the Auger Core-Valence-Valence decay: Simplified Approach. https://doi.org/10.1103/physrevb.60.11391

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