Berlin 2005 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 16: Posters Correlated Electrons, Measuring Devices, Cryotechnique
TT 16.84: Poster
Samstag, 5. März 2005, 11:00–16:30, Poster TU C
Generalization of Luttinger-Ward Functional and the Extended Variational Cluster Approach — •Ninghua Tong1 and Ralf Bulla2 — 1Institute for Theory of Condensed Matter, University of Karlsruhe — 2Theoretical Physics III, Institute for Physics, University of Augsburg
The Luttinger-Ward functional is generalized to a functional of more than one variable. Our generalization is based on the Legendre transformation to the grand potential functional, and therefore does not rely on the perturbative diagram analysis. Combining it with the idea of variational cluster approach (VCA), we obtain an extended VCA theory. In this theory, both non-interacting and interacting part of the reference Hamiltonian can be varied to approach the stationary point of a generalized self-energy functional. In the limit of continuous bath degrees of freedom, it can recover the extended dynamical mean-field theory for non-local density-density interaction as well as the dynamical mean-field theory for correlated hopping. We also propose a VCA realization of the dynamical cluster approximation.