Regensburg 2022 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 16: Correlated Electrons: Method Development

TT 16.4: Talk

Wednesday, September 7, 2022, 10:30–10:45, H10

Vertex divergences in the Anderson impurity model - From real to imaginary frequencies — •Michael Meixner¹, Johannes Halbinger², Seung-Sup Lee³, Fabian Kugler⁴, Patrick Chalupa-Gantner⁵, Alessandro Toschi⁵, Jan von Delft², and Thomas Schäfer¹ — ¹Max Planck Institute for Solid State Research, Stuttgart, Germany — ²Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universität München, Munich, Germany — ³Department of Physics and Astronomy, National University, Seoul, South Korea — ⁴Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, USA — ⁵Institute for Solid State Physics, TU Wien, Vienna, Austria

Generalized susceptibilities not only are at the heart of calculating momentum- and frequency-dependent response functions, but can also provide direct physical insights into local magnetic moment formation and Kondo screening. In particular, recent literature has investigated the implications of divergences of the irreducible vertex function on the Matsubara axis in the charge and particle-particle channels on the physics of the Anderson impurity model. In this study we examine the divergent properties of the two-particle irreducible vertex function in the Anderson impurity model employing the numerical renormalization group (NRG). In a first step data is benchmarked against state of the art results from continuous-time quantum Monte Carlo on the imaginary frequency axis. In a second step NRG allows us to access not only imaginary frequencies but also real frequencies via the Keldysh contour at very low temperatures and without analytic continuation.