15 February 2023 Wed 2 pm

In this talk, I will describe a powerful numerical approach for studying strongly correlated systems, which uses the numerical renormalization group (NRG) as an impurity solver of the dynamical mean-field theory (DMFT). Based on recent methodological advances made by my colleagues and me, I have established an NRG method that can handle first-principles calculations and nonlocal electronic correlations. It provides accurate real-frequency dynamical properties for low system temperatures, which goes beyond the reach of other methods, such as quantum Monte Carlo. Such strengths are demonstrated in our studies: We clarified the key characteristics of Hund metals, namely spin-orbital separation [1, 2] and orbital differentiation [3], in model systems as well as strontium ruthenate [4]. We also investigated intriguing quantum critical behaviors in heavy-fermion systems [5]. Last but not least, I will introduce our recent breakthrough in the theory of multipoint correlation functions [6, 7], which describe inelastic scattering and nonlocal correlations.

[1] E. Walter, K. M. Stadler, S.-S. B. Lee*, Y. Wang, G. Kotliar, A. Weichselbaum, and J. von Delft, Phys. Rev. X 10, 031052 (2020).

[2] Y. Wang, E. Walter, S.-S. B. Lee, K. M. Stadler, J. von Delft, A. Weichselbaum, and G. Kotliar, Phys. Rev. Lett. 124, 136406 (2020).

[3] F. B. Kugler, S.-S. B. Lee, A. Weichselbaum, G. Kotliar, and J. von Delft, Phys. Rev. B 100, 115159 (2019).

[4] F. B. Kugler, M. Zingl, H. U. R. Strand, S.-S. B. Lee, J. von Delft, and A. Georges, Phys. Rev. Lett. 124, 016401 (2020).

[5] A. Gleis, S.-S. B. Lee, A. Weichselbaum, G. Kotliar, and J. von Delft, in preparation.

[6] F. B. Kugler*, S.-S. B. Lee*, and J. von Delft, Phys. Rev. X 11, 041006 (2021). (*: These authors contributed equally to this work.)

[7] S.-S. B. Lee, F. B. Kugler, and J. von Delft, Phys. Rev. X 11, 041007 (2021).

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