Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 78: Electronic Structure of Surfaces I: Photoelectron Spectroscopy

O 78.6: Vortrag

Donnerstag, 4. April 2019, 12:00–12:15, H14

Impact of collective electrostatic effects on the calculation of core-level excitations within the final state approach — •Thomas C. Taucher, Oliver T. Hofmann, and Egbert Zojer — Institute of Solid State Physics, Graz University of Technology, NAWI Graz, Petersgasse 16, 8010 Graz, Austria

In this contribution we discuss complications arising when applying slab-type density functional theory-based band structure calculations to model core-level excitations at metal-organic interfaces:

When performing calculations using the final state approach, a possible complication is that by exciting an electron in every unit cell, an artificial dipole layer is created. Such dipole layers shift the core-level energies.[1] When adsorbing polar molecules, the shift due to the induced dipole layer is consistent with the actual experimental situation, while in the above mentioned final state calculations, the resulting shifts are artificial.

As a strategy to tackle this issue, we suggest to use larger supercells for the calculations. In this case, the surface coverage stays the same, but only a tiny fraction of the molecules is excited. This approach resembles the actual X-ray photoelectron spectroscopy experiments in a much better way, and is pushing the limitations of today’s computational resources.

[1] T. C. Taucher et al., J. Phys. Chem. C, 2016, 120, 3428.