Berlin 2008 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 30: Electron Theory

MA 30.10: Vortrag

Donnerstag, 28. Februar 2008, 17:00–17:15, H 1028

Towards a linear-scaling algorithm for density-functional calculation for metallic systems — •Rudolf Zeller — Institut für Festkörperforschung, Forschungszentrum Jülich GmbH, 52425 Jülich

Linear-scaling algorithms for electronic structure calculations are usually based on a truncation of the density matrix, which decays exponentially in band gap systems. For metallic systems, however, it is not yet well understood whether the decay is fast enough or can be made so by introducing finite temperatures. These questions were investigated with the tight-binding (screened) Korringa-Kohn-Rostoker Green-function method. In calculations for large Cu and Pd supercells with fcc geometry, a spatial truncation of the Green function was applied and the dependence of total energy error on the truncation radius was determined. For reasonable electronic temperatures it was found that the error was bounded by about 2 meV per atom if a few thousand atoms are contained in the truncation range. It is shown that a fixed truncation radius leads to a computational effort per atom, which is independent of the number of atoms in the system, if the sparse matrix equations, which arise because of the tight-binding (screening) transformation, are solved iteratively. This linear-scaling feature and a straightforward parallelization strategy over the atoms opens the way to calculate the electronic and magnetic structure of large metallic systems on massively parallel computers.