Regensburg 2025 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 17: Correlated Electrons: Method Development
TT 17.12: Talk
Tuesday, March 18, 2025, 12:30–12:45, H33
Cluster extension of the DMF2RG and application to the 2d Hubbard model — •Marcel Krämer1,2, Michael Meixner1, Kilian Fraboulet1, Pietro Bonetti3, Demetrio Vilardi1, Nils Wentzell4, Thomas Schäfer1, Alessandro Toschi5, and Sabine Andergassen2,5 — 1Max Planck Institute for Solid State Research, Stuttgart, Germany — 2Institute of Information Systems Engineering, TU Wien, Vienna, Austria — 3Department of Physics, Harvard University, Cambdrige, USA — 4Center for Computational Quantum Physics, Flatiron Institute, New York, USA — 5Institute for Solid State Physics, TU Wien, Vienna, Austria
The DMF2RG has been introduced to overcome the weak-coupling limitation of the fermionic functional renormalization group (fRG). This approach builds on the idea to exploit the dynamical mean-field theory (DMFT) as starting point for the fRG flow, thus capturing local nonperturbative correlations via DMFT together with perturbative nonlocal correlations generated during the flow. We show how nonlocal nonperturbative correlations can be also incorporated in the DMF2RG scheme by using cellular DMFT (CDMFT) for a 2 × 2 cluster instead of single-site DMFT as starting point of the flow. Both CDMFT and fRG implementations have been formulated within the single-boson exchange decomposition, which has already proven to be an insightful bosonization scheme. We illustrate the ability of this novel approach to efficiently capture nonlocal nonperturbative correlations to describe d-wave superconductivity in the 2d Hubbard model.
Keywords: Hubbard model; Dynamical mean-field theory; Functional renormalization group