Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 2: Focussed session: Frontiers of electronic structure theory: Strong correlations from first principles I (jointly with TT)
O 2.7: Vortrag
Montag, 26. März 2012, 12:30–12:45, HE 101
Valence-band correlations and core hole effects in the x-ray absorption and magnetic circular dichroism spectra — •Ondřej Šipr1, Stephan Borek2, Angelika Chassé2, Hubert Ebert3, and Jan Minár3 — 1Institute of Physics AS CR v.v.i., Praha, Czech Republic — 2Institut für Physik, Martin-Luther-University Halle-Wittenberg, Germany — 3Department Chemie, Universität München, Germany
A quantitative description of the x-ray absorption spectra (XAS) and x-ray circular magnetic dichroism spectra (XMCD) should account for correlations between valence electrons in the initial state and for a core hole in the final state. We employ the local spin density approximation (LSDA) plus dynamical mean field theory (DMFT) formalism to describe the correlations between the d electrons and the linear-response theory within the time-dependent density-functional-theory (TDDFT) to describe the core hole. The most important effects beyond the LSDA are thus included and yet the scheme is computationally tractable.
The impact of many-body effects on XAS and XMCD is assessed by investigating L2,3-edge spectra of 3d transition metals. We find that the LSDA+DMFT alone improves the LSDA results, in particular concerning the asymmetry of the L3 white line. To get more accurate results, particularly concerning the ratio of the intensities of the L3 and L2 peaks, the dynamic aspects of the core hole have to be included via the TDDFT linear response framework. Similar conclusions follow also from our study of Heusler alloys (Cu2MnAl).
The work was supported by projects SFB 762 and P108/11/0853.