  We develop a diagrammatic approach with local and nonlocal self-energy
diagrams, constructed from the local irreducible vertex. This approach includes
the local correlations of dynamical mean field theory and long-range
correlations beyond. It allows for example to describe (para-)magnons and weak
localization effects in strongly correlated systems. As a first application, we
study the interplay between nonlocal antiferromagnetic correlations and the
strong local correlations emerging in the vicinity of a Mott-Hubbard
transition.
