Fierz Convergence Criterion: A Controlled Approach to Strongly Interacting Systems with Small Embedded Clusters

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dc.citation.issue16
dc.citation.rankM21a
dc.citation.spage166401
dc.citation.volume119
dc.contributor.authorAyral, Thomas
dc.contributor.authorVučičević, Jakša
dc.contributor.authorParcollet, Olivier
dc.date.accessioned2024-07-26T12:54:02Z
dc.date.available2024-07-26T12:54:02Z
dc.date.issued2017-10-16
dc.description.abstractWe present an embedded-cluster method, based on the triply irreducible local expansion formalism. It turns the Fierz ambiguity, inherent to approaches based on a bosonic decoupling of local fermionic interactions, into a convergence criterion. It is based on the approximation of the three-leg vertex by a coarse-grained vertex computed from a self-consistently determined cluster impurity model. The computed self-energies are, by construction, continuous functions of momentum. We show that, in three interaction and doping regimes of the two-dimensional Hubbard model, self-energies obtained with clusters of size four only are very close to numerically exact benchmark results. We show that the Fierz parameter, which parametrizes the freedom in the Hubbard-Stratonovich decoupling, can be used as a quality control parameter. By contrast, the GW+extended dynamical mean field theory approximation with four cluster sites is shown to yield good results only in the weak-coupling regime and for a particular decoupling. Finally, we show that the vertex has spatially nonlocal components only at low Matsubara frequencies.
dc.identifier.issn0031-9007
dc.identifier.issn1079-7114
dc.identifier.scopus2-s2.0-85031904120
dc.identifier.urihttps://pub.ipb.ac.rs/handle/123456789/184
dc.identifier.wos000413053700007
dc.language.isoen
dc.publisherAmerican Physical Society
dc.relation.ispartofPhysical Review Letters
dc.relation.ispartofabbrPhys. Rev. Lett.
dc.rightsrestrictedAccess
dc.titleFierz Convergence Criterion: A Controlled Approach to Strongly Interacting Systems with Small Embedded Clusters
dc.typeArticle
dc.type.versionpublishedVersion
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