Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 4: Electronic Structure of Surfaces I
O 4.6: Vortrag
Montag, 16. März 2015, 11:45–12:00, MA 041
One- and many-electron computational scheme for XES and NEXAFS spectra calculation within DFT and pseudopotential approach — •Roman Ovcharenko1, Elena Voloshina1, Alexander Shulakov2, and Yuriy Dedkov3 — 1Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489 Berlin, Germany — 2V. A. Fock Institute of Physics, Saint-Petersburg State University, 198504 Saint-Petersburg, Russia — 3SPECS Surface Nano Analysis GmbH, Voltasraße 5, 13555 Berlin, Germany
In this work we present the density functional method using the PAW pseudopotential and the plane wave basis set for X-ray emission and absorption spectra calculation of simple metals and graphene-like systems. As it is well known, smoothed pseudo wave functions differ from the standard all-electron crystal orbitals in the atomic core region which is particularly important for X-ray matrix elements calculation. Therefore, to calculate the probabilities of X-ray spectra, we have reconstructed all-electron orbitals in the core region leaving wave function outside core sphere unchanged.
Moreover, even after such reconstruction many materials demonstrate spectral features which cannot be described by one-electron treating. The problem is in originally many particle nature of the dynamical core-hole screening during X-ray transition, which partially can be overcome by adopting Mahan-Nozieres-De Dominicis theory. The results of numerical application of such one- and many-electron approaches to a number of simple metals as well as graphene-like systems is the topic of present talk.