The LDA+DMFT approach to strongly correlated materials

Soon after the discovery of the basic principles of quantum mechanics theorists set out to explain the properties of solids from a first-principles, atomistic perspective. However, it soon became clear that theoretical methods based on the calculation of fermionic many-particle wave functions are notoriously difficult to handle. A crucial step forward was density-functional theory (DFT) and its local-density approximation (LDA). The success of DFT in explaining the physical and chemical properties of solids is remarkable. Nevertheless, LDA and its generalizations fail for systems whose low-energy properties are dominated by electron-electron correlations, such as Mott-insulating transition-metal oxides, Kondo and heavy-fermion materials, organic crystals, and many others. The realistic description of these strongly correlated materials remains, to date, one of the grand challenges of condensed matter-physics. During the last few years conventional band-structure calculations in the local density approximation (LDA) have been merged with a modern many-body approach, the dynamical mean-field theory (DMFT), into a novel computational method referred to as LDA + DMFT. This framework has proved to be a breakthrough for the realistic modeling of the electronic, magnetic, and structural properties of materials such as transition metals and their oxides. Nevertheless the LDA + DMFT approach still needs to be considerably advanced to be able to treat increasingly complex systems. This requires, for example, an improvement of the interface between the band structure and many-body constituents of the approach, the refinement and integration of efficient impurity solvers, the realistic computation of free energies and forces, and the development of schemes to treat non-local correlations. For this purpose 25 researchers from 16 different institutions in the German-speaking part of Europe joined forces and established the Research Unit FOR 1346 on $\textit{Dynamical Mean-Field Approach with Predictive Power for Strongly Correlated Materials}$, which is funded by the Deutsche Forschungsgemeinschaft since July 2010. It is the goal of this Research Unit to develop the LDA + DMFT framework into a comprehensive $\textit{ab initio}$ approach which will be able to describe, and eventually even predict, the properties of complex correlated materials. By organizing the 2011 Autumn School $\textit{Hands-on LDA + DMFT}$ the researchers of the DFG Research Unit FOR 1346 offer a practical introduction into the LDA + DMFT approach for graduate students and young researchers in this novel branch of condensed matter physics. The school covers the following topics [...