Berlin 2024 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 86: Correlated Electrons: Method Development

TT 86.8: Talk

Friday, March 22, 2024, 11:30–11:45, H 3007

Inchworm quasi Monte Carlo for quantum impurities — •Hugo U. R. Strand^1,2, Joseph Kleinhenz³, and Igor Krivenko⁴ — ¹School of Science and Technology, Örebro University, SE-701 82 Örebro, Sweden — ²Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, the Netherlands — ³Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720-8229, USA — ⁴Institut für Theoretische Physik, Universität Hamburg, Notkestraße 9, 22607 Hamburg, Germany

The inchworm expansion is a promising approach to solving strongly correlated quantum impurity models due to its reduction of the sign problem in real and imaginary time. We show that the imaginary time integration is amenable to quasi Monte Carlo, with enhanced N⁻¹ convergence, compared to standard inchworm Monte Carlo calculations with N^−1/2 convergence. This extends the applicability of the inchworm method to, e.g., multi-orbital Anderson impurity models with off-diagonal hybridization, relevant for materials simulation, where continuous time hybridization expansion Monte Carlo has a severe sign problem. We also present an open source implementation of our Inchworm quasi Monte Carlo approach: “QInchworm.jl”, implemented in the Julia programming language.

Keywords: impurity models; strong coupling expansion; quasi Monte Carlo; inchworm; open source