Regensburg 2013 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 58: Poster Session III (Solid-liquid interfaces; Scanning probe and other methods; Electronic structure theory; Spin-orbit interaction)

O 58.77: Poster

Mittwoch, 13. März 2013, 18:15–21:45, Poster B1

Benchmarking G₀W₀ for small metal clusters using exact frequency treatment — •Ferdinand Kaplan¹, Michiel van Setten¹, and Ferdinand Evers² — ¹Institute of Nanotechnoloy, Karlsruhe Institute of Technology, Germany — ²Institute of Theoretical Condensed Matter, Karlsruhe Institute of Technology, Germany

One of the most used approaches for the computational study of solids, nanoscale systems and molecules is the density functional theory (DFT). However, as is well known, DFT calculations of single particle excitation spectra, e.g. ionization potentials and electron affinities, often suffer from approximations in exchange correlations potentials. More importantly, even fundamental difficulties exist with the common practice to identify the Kohn-Sham particles of ground-state DFT with the genuine quasi-particles.

To systematically improve the estimation of quasi-particle energies for molecular system, we have implemented the so called GW method into a standard quantum chemistry package (G₀W₀-level). The approach represents a perturbative expansion of the many-body Green’s function with respect to the screened interaction, W.

Here, we present applications of the method to small metal cluster systems. First, we show that our implementation works well also in the metallic case where the HOMO-LUMO gap is relatively small, so that one might expect problems for standard perturbative results. Second, we find that deviations from experimental ionization potentials and electron affinities can be reduced against those of Kohn Sham-DFT using PBE functionals.