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TT: Fachverband Tiefe Temperaturen
TT 91: Correlated Electrons: Method Development
TT 91.3: Talk
Thursday, March 15, 2018, 15:30–15:45, H 0104
Phase transitions with a fully consistent second order functional renormalization group scheme — •Lisa Markhof1, Björn Sbierski2, Volker Meden1, and Christoph Karrasch2 — 1Inst. for Theory of Stat. Phys., RWTH Aachen, Germany — 2Dept. of Phys., FU Berlin, Germany
The functional renormalization group (fRG) is a versatile tool to tackle interacting many-body systems [1]. Recently, starting from the generic flow equations, the “extended coupled-ladder approximation” (eCLA) for specific models has been developed which is exact up to second order in the interaction [2,3], while still being feasible from a computational point of view. We here employ this scheme to study phase transitions in models of spinless fermions. Using a channel decomposition and exploiting the structure of the bare interaction, all second order terms can be included while keeping the number of flow equations managable. In contrast to other fRG schemes used earlier to investigate phase transitions [1], the self-energy feedback is fully contained as well. It is furthermore possible to incorporate a feedback of the vertex flow. In this approximation, the fRG captures phase transitions in one-dimensional tight-binding chains at half filling, which are inaccessible to a lowest order fRG scheme. We apply the eCLA to models in real space; a similar approach has been used in [4] in momentum space.
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S. Sbierski and C. Karrasch, arXiv:1710.06373