title: Variational cluster approach to correlated electron systems in low dimensions.
abstract: A self-energy-functional approach is applied to construct cluster approximations for correlated lattice models. It turns out that the cluster-perturbation theory [Phys. Rev. Lett. 84, 522 (2000)]] and the cellular dynamical mean-field theory [Phys. Rev. Lett. 87, 186401 (2001)]] are limiting cases of a more general cluster method. The results for the one-dimensional Hubbard model are discussed with regard to boundary conditions, bath degrees of freedom, and cluster size.
authors.affiliation: Institut für Theoretische Physik, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Potthoff
authors.forename: M
authors.initials: M
authors.lastname: Aichhorn
authors.forename: C
authors.initials: C
authors.lastname: Dahnken