Local-field and excitonic effects in the optical response of alpha-alumina

A. G. Marinopoulos, Myrta Gruening

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Abstract

This paper introduces key ingredients of the dielectric response of a-alumina that go beyond an independent-particle (IP) treatment of the valence-electron excitations. The optical-response functions were calculated from first-principles both at the Bethe-Salpeter and the random-phase approximation (RPA) levels. Excitonic effects obtained within the Bethe-Salpeter framework were found essential for reproducing the low-energy part of the experimental spectra (below 15 eV) and the bound exciton in particular. For higher energies, local-field effects introduced through the RPA modified considerably the IP results and provided a satisfactory account of the reflectivity spectra and of the position and shape of the dominant bulk plasmon resonance in the electron energy-loss spectra.

Original languageEnglish
Article number195129
Pages (from-to)-
Number of pages9
JournalPhysical Review B (Condensed Matter)
Volume83
Issue number19
DOIs
Publication statusPublished - 25 May 2011

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