Mixed-configuration approximation for multi-orbital systems out of equilibrium

Fuente: arXiv
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Autori principali: Mazzocchi, Tommaso Maria, Werner, Daniel, Aichhorn, Markus, Arrigoni, Enrico
Natura: Preprint
Pubblicazione: 2025
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author Mazzocchi, Tommaso Maria
Werner, Daniel
Aichhorn, Markus
Arrigoni, Enrico
author_facet Mazzocchi, Tommaso Maria
Werner, Daniel
Aichhorn, Markus
Arrigoni, Enrico
contents We propose a mixed-configuration approximation based on single-band impurity solvers to efficiently study nonequilibrium multi-orbital systems at moderate computational cost. In this work, we merge the approach with the so-called auxiliary master equation approach. As benchmark, we first show that our approach reproduces the results of quantum Monte Carlo (QMC) for two-orbital impurity models at equilibrium with overall good accuracy, especially for non-degenerate orbitals. We then use our approach as impurity solver for dynamical mean-field theory (DMFT) to address the case of a two-orbital, realistic layered structure, recovering the strong crystal-field-driven charge polarization observed by solving the DMFT self-consistent cycle with QMC, albeit slightly reduced. Finally, we address a prototype nonequilibrium setup by sandwiching this layer between metallic contacts subject to a bias voltage described by different chemical potentials. This simplified model demonstrates out method's potential to access nonequilibrium steady-state behavior of multi-orbital, realistic materials. These findings provide a first-step basis for theoretical studies of nonequilibrium properties of multi-orbital compounds directly in the real frequency domain.
format Preprint
id arxiv_https___arxiv_org_abs_2507_10717
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Mixed-configuration approximation for multi-orbital systems out of equilibrium
Mazzocchi, Tommaso Maria
Werner, Daniel
Aichhorn, Markus
Arrigoni, Enrico
Strongly Correlated Electrons
We propose a mixed-configuration approximation based on single-band impurity solvers to efficiently study nonequilibrium multi-orbital systems at moderate computational cost. In this work, we merge the approach with the so-called auxiliary master equation approach. As benchmark, we first show that our approach reproduces the results of quantum Monte Carlo (QMC) for two-orbital impurity models at equilibrium with overall good accuracy, especially for non-degenerate orbitals. We then use our approach as impurity solver for dynamical mean-field theory (DMFT) to address the case of a two-orbital, realistic layered structure, recovering the strong crystal-field-driven charge polarization observed by solving the DMFT self-consistent cycle with QMC, albeit slightly reduced. Finally, we address a prototype nonequilibrium setup by sandwiching this layer between metallic contacts subject to a bias voltage described by different chemical potentials. This simplified model demonstrates out method's potential to access nonequilibrium steady-state behavior of multi-orbital, realistic materials. These findings provide a first-step basis for theoretical studies of nonequilibrium properties of multi-orbital compounds directly in the real frequency domain.
title Mixed-configuration approximation for multi-orbital systems out of equilibrium
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2507.10717