Influence of Electron-Electron Correlations and Lattice Effects on Positron-Electron Enhancement Factors

Abstract:

We present an approach taking into account the effect of electron-electron (e-e) correlations on electron-positron (e-p) momentum density distributions. The approach bases on the modification of the Bethe-Goldstone (B-G) equation for the positron in the electron gas due to self-energy effects. The example calculations have been performed for selected parameters corresponding to simple metals. The calculated dependencies exhibit the increase of the e-p enhancement factors below Fermi momentum, like Kahana enhancements, and a decrease above the Fermi sphere, leading to a many-body “tail” in the e-p momentum density distributions. Moreover, the influence of lattice effects on enhancement factors (EF) is taken into account. This decreases by a few percent the absolute values of the e-p momentum distributions and the corresponding annihilation rates and for real metals such as Mg or Cu evidently improve the agreement with experiment.

• Periodical: Materials Science Forum (Volume 666)
• Pages: 5-9
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.666.5
• Online since: December 2010
• Authors: Edward Boroński
• Keywords: Electronic Structure, Positron Annihilation

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