Dresden 2017 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 5: Correlated Electrons: (General) Theory 1

TT 5.2: Talk

Monday, March 20, 2017, 09:45–10:00, HSZ 304

Impact of nonlocal correlations over different energy scales: A dynamical vertex approximation study — •Georg Rohringer¹ and Alessandro Toschi² — ¹Russian Quantum Center, Moscow (Russia) — ²Technische Universität Wien (Austria)

We investigate [1] how nonlocal correlations affect, selectively, the physics of correlated electrons over different energy scales, from the Fermi level to the band edges. This goal is achieved by the dynamical vertex approximation (DΓA), studying several spectral and thermodynamic properties of the unfrustrated Hubbard model in 2d and 3d. Specifically, we focus first on the low-energy regime by computing the electronic scattering rate and the quasiparticle mass renormalization for decreasing temperatures at a fixed interaction strength. This way, we obtain a precise characterization of the several steps through which the Fermi-liquid physics is progressively destroyed by nonlocal correlations. Our study is then extended to a broader energy range, by analyzing the temperature behavior of the kinetic and potential energy, as well as of the corresponding energy distribution functions. Our findings allow us to identify a smooth but definite evolution of the nature of nonlocal correlations by increasing interaction. Finally, a critical analysis of our numerical results of the potential energy at the largest interaction allows us to identify possible procedures to improve state-of-the-art algorithms beyond DMFT.

[1] G. Rohringer and A. Toschi, Phys. Rev. B 94, 125144 (2016).