Dresden 2017 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 19: Poster Session: Correlated Electrons 1

TT 19.37: Poster

Monday, March 20, 2017, 15:00–19:00, P2-EG

Mean-field extension of the variational cluster approach — •Jan Lotze and Maria Daghofer — Universität Stuttgart, Institut für Funktionelle Materie und Quantentechnologien, Pfaffenwaldring 57, 70550 Stuttgart

The variational cluster approximation (VCA) based on self-energy functional theory (SFT) can be used to study correlated-electron Hamiltonians: Instead of the original systems self-energy, that of a ’reference system’ is considered. Both systems must share the same two-body interactions, but may differ in one-body terms such as the kinetic hopping. Within VCA, the reference system is formed by isolated clusters. From the SFT perspective, inter-site interactions cannot be included. We propose to incorporate interactions along bonds inside the clusters exactly, while those between clusters are mean-field decoupled. Although this is an approximation, it should be controlled by the cluster-size as for pure VCA.

Results obtained for the extended Hubbard model in one and two dimensions on a square [1] and a honeycomb lattice [2] are shown.

[1] M. Aichhorn, H. G. Evertz, W. von der Linden and M. Potthoff, Phys. Rev. B 70, 235107 (2004)

[2] M. Daghofer and M. Hohenadler, Phys. Rev. B 89, 035103 (2014)