Dieter Vollhardt
Dieter Vollhardt (born September 8, 1951) is a German physicist and Professor of Theoretical Physics at the University of Augsburg. Scientific work. Vollhardt is one of the founders of the Dynamical Mean-Field Theory (DMFT) for strongly correlated materials such as transition metals (e.g. iron or vanadium) and their oxides, i.e. materials with electrons in open d- and f-shells. The properties of these systems are determined by the Coulomb repulsion between the electrons which makes these electrons strongly correlated. The repulsion has the tendency to localize electrons. This leads to a multitude of phenomena such as the  Mott-Hubbard metal insulator transition. Conventional band theory or density functional theory cannot describe these systems adequately. In 1989 Vollhardt and his doctoral student Walter Metzner introduced electronic models with local interaction (Hubbard model) on a lattice with infinitely many nearest neighbors, which Gabriel Kotliar and Antoine Georges then developed into the DMFT. The DMFT may be viewed as a self-consistent, field-theoretical generalization of a quantum impurity model by Philip W. Anderson, where the mean-field describes the coupling of the impurity to an "electronic bath". DMFT provides an exact description of the quantum dynamics of correlated  lattice systems with local interaction, but neglects spatial correlations. It has provided fundamental insights into the properties of correlated electronic systems. The combination of the DMFT with material-specific approaches, such as the "Local Density Approximation" (LDA) to the density functional theory, led to a new computational scheme, often referred to as LDA+DMFT, for the investigation of strongly correlated materials.