# Berlin 2015 – wissenschaftliches Programm

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# TT: Fachverband Tiefe Temperaturen

## TT 86: Correlated Electrons: (General) Theory 2

### TT 86.4: Vortrag

### Donnerstag, 19. März 2015, 10:15–10:30, H 3005

**Interplay between Point-Group Symmetries and the Choice of the Bloch Basis in Multiband Models** — •Stefan A. Maier^{1} and Carsten Honerkamp^{1,2} — ^{1}Institute for Theoretical Solid State Physics, RWTH Aachen University, D-52056 Aachen, Germany — ^{2}Member of JARA-FIT, Jülich-Aachen Research Alliance–Fundamentals of Future Information Technology

We analyze the point-group symmetries of generic multiband tight-binding models with respect to the transformation properties of the effective interactions. While the vertex functions in the orbital language may transform non-trivially under point-group operations, their point-group behavior in the band language can be simplified by choosing a suitable Bloch basis. We show that, for a large class of models, a natural Bloch basis exists, in which the vertex functions in the band language transform trivially under all point-group operations [cf. our article in *Symmetry*, **5(4)**, 313 (2013)]. As a consequence, the point-group symmetries can be used to reduce the computational effort in perturbative many-particle approaches, such as the functional renormalization group.