Practical consequences of the Luttinger-Ward functional multivaluedness for cluster DMFT methods

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dc.citation.issue12
dc.citation.rankM21
dc.citation.spage125141
dc.citation.volume97
dc.contributor.authorVučičević, Jakša
dc.contributor.authorWentzell, Nils
dc.contributor.authorFerrero, Michel
dc.contributor.authorParcollet, Olivier
dc.date.accessioned2024-07-03T08:15:37Z
dc.date.available2024-07-03T08:15:37Z
dc.date.issued2018-03-23
dc.description.abstractThe Luttinger-Ward functional (LWF) has been a starting point for conserving approximations in many-body physics for 50 years. The recent discoveries of its multivaluedness and the associated divergence of the two-particle irreducible vertex function Γ have revealed an inherent limitation of this approach. Here we demonstrate how these undesirable properties of the LWF can lead to a failure of computational methods based on an approximation of the LWF. We apply the nested cluster scheme (NCS) to the Hubbard model and observe the existence of an additional stationary point of the self-consistent equations, associated with an unphysical branch of the LWF. In the strongly correlated regime, starting with the first divergence of Γ, this unphysical stationary point becomes attractive in the standard iterative technique used to solve DMFT. This leads to an incorrect solution, even in the large cluster size limit, for which we discuss diagnostics.
dc.identifier.doi10.1103/physrevb.97.125141
dc.identifier.issn2469-9950
dc.identifier.issn2469-9969
dc.identifier.scopus2-s2.0-85044446748
dc.identifier.urihttps://pub.ipb.ac.rs/handle/123456789/173
dc.identifier.wos000428162200004
dc.language.isoen
dc.publisherAmerican Physical Society
dc.relation.ispartofPhysical Review B
dc.relation.ispartofabbrPhys. Rev. B
dc.rightsrestrictedAccess
dc.titlePractical consequences of the Luttinger-Ward functional multivaluedness for cluster DMFT methods
dc.typeArticle
dc.type.versionpublishedVersion
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