# Berlin 2018 – wissenschaftliches Programm

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# O: Fachverband Oberflächenphysik

## O 28: Electronic Structure Theory: General I

### O 28.5: Vortrag

### Dienstag, 13. März 2018, 11:30–11:45, MA 141

**The Kohn-Sham gap as example for an explicit density functional** — •Martin Panholzer^{1,3}, Matteo Gatti^{2,3}, and Lucia Reining^{2,3} — ^{1}Johannes Kepler University, Linz, Austria — ^{2}Laboratoire des Solides Irradies, Ecole Polytechnique, CNRS, CEA, Universite Paris-Saclay , F-91128 Palaiseau, France — ^{3}European Theoretical Spectroscopy Facility (ETSF)

It is well known that the density fully characterizes the ground state of a system. The use of the total energy as a functional of the density led to the usual implementation of Kohn-Sham(KS)-DFT. But other quantities, apart from the total energy, are rarely investigated. In this work we examine the KS-gap as a functional of the density. Numerically the inversion of the KS-equation is done iteratively. Different schemes are compared.

A purpose of the work is to investigate the sensitivity of a system to inaccuracies in the density, especially in view of a subsequent calculation of excited state properties. The KS-gap acts here as an easily accessible indicator.

We also use the density-functional formulation for the band gap to discuss the relation between the Kohn-Sham gap and the electron addition and removal gap.