Field of Expertise: Advanced Material Science

Efficient cluster-based solvers for dynamical mean-field theory
Manuel Zingl
15:00 - 17:00 Thursday 23 October 2014 Rechbauerstrasse 12, HSII

The physics of materials with strongly correlated electrons is one of the most fascinating topics in modern solid-state research. Standard band structure methods often provide even qualitatively wrong results and are not suitable for an accurate description of such systems and thus a many-body approach based on model Hamiltonians is required. One of the most successful methods available for strongly correlated materials is the dynamical mean-field theory (DMFT). To solve the self-consistent set of DMFT equations, it is necessary to determine the Green’s function of the so-called Anderson impurity model. The main aim of this work is the development and the implementation of a new impurity solver based on exact diagonalization and an adapted version of cluster perturbation theory.
We test our method on the infinitely connected Bethe lattice by comparing the self-energy as well as the density of states to results obtained with exact diagonalization and other impurity solvers. Additionaly, we modify our solver to allow a treatment of multi-orbital impurity systems in the framework of DFT+DMFT, which is a general approach to combine density functional theory (DFT) calculations with a successive application of DMFT to the strongly correlated subspace. The transition metal oxide SrVO3 with its cubic crystal structure is chosen as a benchmark material.