PROJECTS

Electronic Structure and Excitation Spectra of Magnetic Materials
within First-Principles Many-Body Perturbation Theory

PRINCIPAL INVESTIGATOR

Prof. Dr. Arno Schindlmayr Universität Paderborn Department Physik Warburger Straße 100 33095 Paderborn Germany 05251/602338 05251/603435 Arno.Schindlmayr@uni-paderborn.de www: Homepage

TOGETHER WITH

Dr. Gustav Bihlmayer Forschungszentrum Jülich GmbH Institut für Festkörperforschung 52425 Jülich Germany 02461/614677 02461/612850 G.Bihlmayer@fz-juelich.de www: Homepage

Prof. Dr. Stefan Blügel Forschungszentrum Jülich GmbH Institut für Festkörperforschung 52425 Jülich Germany 02461/614249 02461/612850 S.Bluegel@fz-juelich.de www: Homepage

PROJECT RESEARCH ASSISTANT

ABSTRACT

We develop a computational method based on many-body perturbation theory to enable first-principles calculations of the electronic structure and excitation spectra of magnetic materials, including single quasiparticle and collective magnon excitations as well as their mutual interaction. In the first phase we implemented the GW approximation for the electronic self-energy within the all-electron FLAPW method, which allows spin-polarized quasiparticle calculations but only includes the coupling to charge fluctuations, not to spin fluctuations. In the second phase we then developed tools to determine materialspecific magnon spectra from the transverse spin susceptibility, using either many-body perturbation theory or time-dependent density-functional theory. In the final phase of the project we now plan to combine the previous achievements in order to study the effect of magnon scattering on the electronic self-energy, which may strongly influence the lifetime of quasiparticle excitations. The principal computational task is the inclusion of the T-matrix that couples electrons and holes in the two spin channels. To reduce the numerical cost associated with the construction of this four-point function without compromising first-principles accuracy, we exploit a transformation to maximally localized Wannier functions that takes advantage of the short-range nature of the correlation. We will use the resulting code to quantitatively examine the dynamics of electronic excitations, especially their lifetimes, in selected magnetic bulk and surface systems.