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TT: Fachverband Tiefe Temperaturen
TT 13: Correlated Electrons: Method Development I
TT 13.7: Vortrag
Montag, 9. März 2026, 16:45–17:00, HSZ/0101
Non-perturbative effects of short-range spatial correlations at the two-particle level — •Michael Meixner1, Matthias Reitner2, Thomas Schäfer1,3, and Alessandro Toschi2 — 1Max-Planck-Institute for Solid-State Research, Stuttgart, Germany — 2TU Wien, Vienna, Austria — 3University of Trieste, Trieste, Italy
Non-local correlations have a strong impact on the electronic dynamics of the square lattice Hubbard model. Specifically, the Mott metal-insulator transition (MIT) occurs at lower interactions when including spatial correlations to the local model via cellular dynamical mean field theory (CDMFT). We present the Bethe-Salpeter equation (BSE) of the charge response and corresponding Ward identities applicable to the CDMFT. The scheme is employed to study the impact of real space bosonic correlations between the impurity sites onto the lattice thermodynamic derivatives such as the charge response. Firstly, we report the occurrence of the break down of self-consistent perturbation theory in the charge channel by observation of the divergence of the irreducible vertex. This is, we find, a precursor of the thermodynamic instability of CDMFT and the corresponding suppression of the charge response at the metal-insulator transition. Secondly, for both phenomena, we underline the essential role of next-neighbour spin correlations.
Keywords: Mott transition; Real-space correlations; Cellular DMFT; Hubbard model; Square lattice