X-ray Absorption and Scattering Spectroscopy in Solids from Many-Body Perturbation Theory
19th. Dec. 2017, Vortrag, Raum MG 272, Lotharstraße 1, 47057 Duisburg
Time:
Start: 19th. Dec. 2017. 10:00 a.m.
End: 19th. Dec. 2017. 12:00
Author(s):
Christian Vorwerk Humboldt University of Berlin
Organizer(s):
Prof. Björn Sothmann Universität Duisburg-Essen
Abstract:
X-ray absorption and inelastic scattering spectroscopy reveal the electronic and structural properties in crystalline materials on the atomic scale through the excitation of tightly-bound electronic core states. The determination of these spectra from first principles requires an accurate description of the electron-core hole interaction, which is typically screened by the surrounding many-electron system. In the approach [1] presented here, core excitations are determined through the solution of the Bethe-Salpeter equation (BSE), which includes the full non-local screened interaction between electron and core hole. Our implementation in the exciting [2] package makes use of Kohn- Sham single-particle energies and wavefunctions for both the core and conduction region, which are obtained from all-electron full-potential DFT calculations on equal footing. To demonstrate our approach, we discuss core spectra of selected bulk materials, ranging from simple oxides, like CaO [1], to complex systems, such as hybrid organic-inorganic perovskites. Our results, in good agreement with available experimental data, provide an in-depth analysis of the excitations, revealing their origin in the band structure and their real-space localization.
References
[1] C. Vorwerk, C. Cocchi, and C. Draxl, Phys. Rev. B 95, 155121 (2017).
[2] A. Gulans et al., J. Phys. Condens. Matter 26, 363202 (2014).