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TT: Fachverband Tiefe Temperaturen
TT 71: Correlated Electrons: Other Theoretical Topics
TT 71.2: Vortrag
Freitag, 20. März 2020, 09:45–10:00, HSZ 304
Constrained Random Phase Approximation: Why and When it Works — •Erik van Loon1, Malte Rösner2, Mikhail Katsnelson2, and Tim Wehling1 — 1Institute for Theoretical Physics and Bremen Center for Computational Materials Science, University of Bremen, Germany — 2Radboud University, Nijmegen, the Netherlands
The constrained Random Phase Approximation (cRPA) is an important part of the modern theory of correlated electron materials. In the downfolding from the full band structure to an effective low-energy (Hubbard) model, the cRPA provides a way to calculate the Hubbard parameter U for the low-energy model, taking into account screening by the other electronic states. Although it is a popular tool, a formal justification for the cRPA has been lacking. Here, we show when the cRPA is a good approximation.