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arXiv · 2407.00771

Steady-state properties of multi-orbital systems using quantum Monte Carlo

Andre Erpenbeck·Thomas Blommel·Lei Zhang·Wei-Ting Lin·Guy Cohen·Emanuel Gull
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Abstract

A precise dynamical characterization of quantum impurity models with multiple interacting orbitals is challenging. In quantum Monte Carlo methods, this is embodied by sign problems. A dynamical sign problem makes it exponentially difficult to simulate long times. A multi-orbital sign problem generally results in a prohibitive computational cost for systems with multiple impurity degrees of freedom even in static equilibrium calculations. Here, we present a numerically exact inchworm method that simultaneously alleviates both sign problems, enabling simulation of multi-orbital systems directly in the equilibrium or nonequilibrium steady-state. The method combines ideas from the recently developed steady-state inchworm Monte Carlo framework [Phys. Rev. Lett. 130, 186301 (2023)] with other ideas from the equilibrium multi-orbital inchworm algorithm [Phys. Rev. Lett. 124, 206405 (2020)]. We verify our method by comparison with analytical limits and numerical results from previous methods.

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Andre Erpenbeck, Thomas Blommel, Lei Zhang, Wei-Ting Lin, Guy Cohen, Emanuel Gull. 2024-06-30. Steady-state properties of multi-orbital systems using quantum Monte Carlo. https://arxiv.org/abs/2407.00771

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