Dresden 2011 – scientific programme

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O: Fachverband Oberflächenphysik

O 83: [MA] Focussed Session "X-ray absorption spectra - state of the art of theory and experiment" (jointly with DS, HL, MM, O)

O 83.1: Invited Talk

Thursday, March 17, 2011, 15:15–15:45, HSZ 403

Simulations of X-ray Spectra using FEFF9 and OCEAN — •John Rehr — University of Washington, Seattle, WA, USA

There has been dramatic recent progress in the theory of x-ray spectra. This spectra probes excited state properties of a system, and thus requires theoretical treatments beyond the independent particle approximation. Here we discuss two complementary approaches based on the GW/BSE method. First is a real-space Green*s function approach, as implemented in the FEFF9 code [1]. FEFF9 has improved treatments of many-body effects and can also include LDA+U corrections. Second, is a new k-space approach implemented in the GW/BSE code OCEAN (Obtaining Core Excitation using ABINIT and NBSE)[2]. OCEAN also includes intra-atomic coulomb interactions and can also treat multiplet effects. FEFF9 and OCEAN have complementary spectral ranges. However, the combination is applicable from the UV-VIS to x-ray energies. These two approaches are illustrated with applications to several core-level specra including XAS and RIXS. This work is supported by US DOE Grant DE-FG03-97ER45623 and the CMCSN. [1]J. J. Rehr et al.,Comptes Rendus Physique 10,548 (2009). [2]J. Vinson et al., arXiv:1010.0025