Regensburg 2016 – scientific programme

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SYES: Symposium Frontiers of Electronic Structure Theory: Focus on Topology and Transport

SYES 8: Frontiers of Electronic Structure Theory: Focus on Topology and Transport

SYES 8.5: Poster

Wednesday, March 9, 2016, 18:15–20:30, Poster A

GW+fRG: Towards an fRG enhancement of ab initio calculations — •Jannis Ehrlich^1,2, Carsten Honerkamp¹, Christoph Friedrich², and Stefan Blügel² — ¹Institut für theoretische Festkörperphysik, RWTH Aachen University, D-52056 Aachen, Germany — ²PGI-1 and IAS-1, FZJ & JARA, D-52425 Jülich, Germany

Spin excitations in solids are of fundamental interest for a wide variety of phenomena. Most materials-specific theoretical studies are based on the adiabatic treatment of the spin-degees of freedom in the context of DFT. Approaches based on the GW approximation include screening effects due to charge fluctuations but neglect vertex corrections and other contributions like magnetic fluctuations. The functional renormalization group (fRG) can overcome these limitations as it resums a different class of diagrams, among them charge and magnetic fluctuations and vertex corrections. We discuss how the equations for two-particle vertices in the fRG contain the GW approximation, the Bethe-Salpeter equation (BSE) and the parquet approach on certain levels of approximations. Thus, a fRG calculation of materials properties could be a powerful approach to improve the GW and BSE methods already applied in first-principles calculations. By using recently suggested channel decomposition schemes [1,2] the method has gained in flexibility and in potential for tackling more complex tasks. Here we propose first steps to develop the fRG approach for the ab initio calculation of materials properties.

[1] C. Husemann, M. Salmhofer, Phys. Rev. B 79, 195125 (2009).

[2] W. Wang et al., Phys. Rev. B 85, 035414 (2012).