Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 36: Methods: Atomic and electronic structure

O 36.1: Vortrag

Dienstag, 23. März 2010, 15:00–15:15, H34

Constructing fully numerical optimum atomic basis-sets — •Björn Lange, Christoph Freysoldt, and Jörg Neugebauer — Max-Planck Institut für Eisenforschung GmbH, 40237 Düsseldorf, Deutschland

Minimum atomic basis-sets as used e.g. for tight-binding calculations are commonly constructed by fitting them or even only their matrix elements to experimental or theoretical data. The resulting models are often optimized only for a specific environment, making a systematic analysis of their transferability impossible. In order to achieve systematically analyzable atom-centered basis-sets, we start from a plane-wave density-functional theory (DFT) calculation where the basis-set convergence is well controlled. The optimum radial shape for each angular momentum channel is determined by maximizing the overlap of the orbitals with the Bloch-states of the underlying plane-wave calculation. While previous approaches employ auxiliary radial basis functions, our orbitals are fully numerical. An analysis of the Bloch state residues shows that part which is not covered by the atomic orbitals and reveals transferability issues and improvement opportunities. To demonstrate the performance of this approach we provide results of an extensive analysis of the transferability characteristics for a wide array of materials such as molecules, semiconductors and metals. Furthermore, we demonstrate the advantages of our basis-sets compared to atomic orbitals obtained from the free atom. For example, detailed convergence checks show that they provide a much better starting point for iterative diagonalization approaches in DFT.