Regensburg 2010 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 37: MLT: Poster Session

TT 37.12: Poster

Thursday, March 25, 2010, 14:00–18:00, Poster A

Variational Cluster Approach for Bosonic Systems — •Stephan Filor and Thomas Pruschke — Institut für Theoretische Physik, Universität Göttingen

We propose a variational cluster ansatz to bosonic systems which is based on Potthoff’s self-energy functional approach. To find a suitable cluster approximation it takes advantage of certain properties of the Baym-Kadanoff formalism which treats the grand canonical potential as a functional of the Green’s function respectively the self-energy.

In our ansatz the bosonic operators are used within the Nambu formalism to allow for a condensed phase, for which we additionally introduce a reservoir coupled to the cluster sites as a variational parameter. The approach is tested for simple lattices.