Regensburg 2019 – wissenschaftliches Programm
CPP 25.32: Poster
Dienstag, 2. April 2019, 14:00–16:00, Poster B1
DFT calculations of K-edge X-ray adsorption spectra for organic molecules — •Rolf Würdemann1, Julia Melke1, Anna Fischer1, and Michael Walter2 — 1Freiburger Materialforschungszentrum, Freiburg, Germany — 2Freiburger Zentrum für interaktive Werkstoffe und bioinspirierte Technologien, Freiburg, Germany
X-ray adsorption spectroscopy (XAS) is an element specific local probe used for the analysis of materials. To compare and interpret these spectra ab initio calculations of XAS spectra can be performed for molecules in given geometries. This can be used to distinguish between different isomers and gain a deeper understanding of the bonding situation.
A common way to calculate XAS spectra by DFT is the utilization of a transition state potential (DFT-TP). In this approach an energetic offset correcting the approximate nature of the used functional has to be applied. To calculate this offset, one has to match the energetic value of the first calculated excitation to experiment. A similar problem in matching energy scales is also known from X-ray photolectron spectroscopy (XPS). Walter et al.[WMP16] have shown, that the offset needed in XPS is nearly constant in respect to the element under con- sideration and its value can be obtained empirically from experimental data.
In our contribution we extend the approach from Walter et al. to the calculation of XAS spectra and compare our results to experiment.
[WMP16] M. Walter et al., Phys. Rev. B 94 (4), 041112, 2016