Extension of the iterated perturbation theory at arbitrary fillings to nonequilibrium steady states

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Main Authors: Mazzocchi, Tommaso Maria, Arrigoni, Enrico
Format: Preprint
Published: 2026
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author Mazzocchi, Tommaso Maria
Arrigoni, Enrico
author_facet Mazzocchi, Tommaso Maria
Arrigoni, Enrico
contents We extend the Kajueter-Kotliar [Phys. Rev. Lett. 77, 131 (1996)] iterated perturbation theory (KK-IPT) away from half filling to nonequilibrium steady states. We benchmark the resulting nonequilibrium KK-IPT approach against the auxiliary master equation approach (AMEA), whose accuracy is controlled in and out of equilibrium. As expected, in equilibrium, KK-IPT reproduces the AMEA results for different fillings with high accuracy at the level of both spectral properties and electron densities. Out of equilibrium, we study quantum transport across a correlated impurity and compute the differential conductance and spectral functions. We find very good agreement between nonequilibrium KK-IPT and AMEA in the parameter regime where the latter is reliable, in particular at moderate temperatures and biases. These results support nonequilibrium KK-IPT as an approximate description of nonequilibrium steady states away from half filling. Although a controlled benchmark is not available in the low-temperature, low-bias regime, where AMEA becomes less reliable, nonequilibrium KK-IPT remains numerically stable in those regions, suggesting that it may provide a useful alternative for nonequilibrium calculations in this regime.
format Preprint
id arxiv_https___arxiv_org_abs_2604_15942
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Extension of the iterated perturbation theory at arbitrary fillings to nonequilibrium steady states
Mazzocchi, Tommaso Maria
Arrigoni, Enrico
Strongly Correlated Electrons
We extend the Kajueter-Kotliar [Phys. Rev. Lett. 77, 131 (1996)] iterated perturbation theory (KK-IPT) away from half filling to nonequilibrium steady states. We benchmark the resulting nonequilibrium KK-IPT approach against the auxiliary master equation approach (AMEA), whose accuracy is controlled in and out of equilibrium. As expected, in equilibrium, KK-IPT reproduces the AMEA results for different fillings with high accuracy at the level of both spectral properties and electron densities. Out of equilibrium, we study quantum transport across a correlated impurity and compute the differential conductance and spectral functions. We find very good agreement between nonequilibrium KK-IPT and AMEA in the parameter regime where the latter is reliable, in particular at moderate temperatures and biases. These results support nonequilibrium KK-IPT as an approximate description of nonequilibrium steady states away from half filling. Although a controlled benchmark is not available in the low-temperature, low-bias regime, where AMEA becomes less reliable, nonequilibrium KK-IPT remains numerically stable in those regions, suggesting that it may provide a useful alternative for nonequilibrium calculations in this regime.
title Extension of the iterated perturbation theory at arbitrary fillings to nonequilibrium steady states
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2604.15942