title: Understanding the electronic structure and magnetism of correlated nanosystems.
abstract: In this paper we review recent developments towards a realistic description of the electronic structure and magnetism of correlated nanosystems. A new class of so-called continuous-time solvers for the quantum impurity problem is discussed, which provides a numerically exact solution without systematic errors due to imaginary time discretization. These solvers are able to handle general interactions, like the full Coulomb vertex. We further show how four-point or higher-order correlation functions of the impurity problem can be computed. This allows the calculation of dynamical susceptibilities which provide information about spin excitations. Moreover, we discuss a principally new many-body scheme recently proposed for the description of non-local correlations in strongly correlated systems. This approach provides a basis for a many-body description of extended correlated nanostructures on a substrate.
authors.affiliation: I. Institute of Theoretical Physics, University of Hamburg, D-20355 Hamburg, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Hafermann
authors.forename: S
authors.initials: S
authors.lastname: Brener
authors.forename: A N
authors.initials: AN
authors.lastname: Rubtsov
authors.forename: M I
authors.initials: MI
authors.lastname: Katsnelson
authors.forename: A I
authors.initials: AI
authors.lastname: Lichtenstein