Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 91: Correlated Electrons: Method Development
TT 91.1: Vortrag
Donnerstag, 15. März 2018, 15:00–15:15, H 0104
Changes in fRG critical scales due to frequency-dependence in a two-patch model — •Timo Reckling and Carsten Honerkamp — Institute for Theoretical Solid State Physics, RWTH Aachen University, 52056 Aachen, Germany
The frequency dependence of the running interactions has become an object of interest in various recent implementations of the functional Renormalization Group (fRG) for low-dimensional fermionic lattice models. In order to understand the main effects and to set up a simpler testbed for approximations, we study a two-patch g-ology model. We analyze the influence of the frequency dependence of the effective two-particle interaction on the critical scales of the flows to strong coupling. To this end the effective interaction which is generated in the fRG flow is parametrized by four interaction components g1,2,3,4 each of which depend on three 3 fermionic Matsubara frequencies. Reducing this dependence on three frequencies defines various approximations, with the static approximation as the most drastic one. We can also switch the frequency dependence on and off in different channels which contain distinct loop contributions on the right hand side of the fRG flow equations. This allows us to gain constructive insight into how the frequency-(in)dependent multi-channel interplay determines the critical scales for ordering instabilities.
This work is supported by the DFG-RTG 1995 "Quantum many-body methods in condensed matter systems".