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Zeitschriftenartikel:

O. Gunnarsson, T. Schäfer, J. p LeBlanc, J. Merino, G. Sangiovanni, G. Rohringer, A. Toschi:
"Parquet decomposition calculations of the electronic self-energy";
Physical Review B, 93 (2016), 245102; S. 1 - 17.



Kurzfassung englisch:
The parquet decomposition of the self-energy into classes of diagrams, those associated with specific scattering
processes, can be exploited for different scopes. In this work, the parquet decomposition is used to unravel the
underlying physics of nonperturbative numerical calculations. We show the specific example of dynamical mean
field theory and its cluster extensions [dynamical cluster approximation (DCA)] applied to the Hubbard model
at half-filling and with hole doping: These techniques allow for a simultaneous determination of two-particle
vertex functions and self-energies and, hence, for an essentially "exact" parquet decomposition at the single-site
or at the cluster level. Our calculations show that the self-energies in the underdoped regime are dominated
by spin-scattering processes, consistent with the conclusions obtained by means of the fluctuation diagnostics
approach [O. Gunnarsson et al., Phys. Rev. Lett. 114, 236402 (2015)]. However, differently from the latter
approach, the parquet procedure displays important changes with increasing interaction: Even for relatively
moderate couplings, well before the Mott transition, singularities appear in different terms, with the notable
exception of the predominant spin channel. We explain precisely how these singularities, which partly limit the
utility of the parquet decomposition and, more generally, of parquet-based algorithms, are never found in the
fluctuation diagnostics procedure. Finally, by a more refined analysis, we link the occurrence of the parquet
singularities in our calculations to a progressive suppression of charge fluctuations and the formation of a
resonance valence bond state, which are typical hallmarks of a pseudogap state in DCA.

Schlagworte:
self-energy calculations, quantum many-body systems, Hubbard model, vertices, parquet equation,pseudogap


"Offizielle" elektronische Version der Publikation (entsprechend ihrem Digital Object Identifier - DOI)
http://dx.doi.org/10.1103/PhysRevB.93.245102



Zugeordnete Projekte:
Projektleitung Alessandro Toschi:
Quantum criticality in strongly correlated magnets


Erstellt aus der Publikationsdatenbank der Technischen Universität Wien.