| speaker: | Frithjof Anders Bremen, Germany |
| time: | We., 15.08, 9:00-10:00 |
I will give an introduction to Wilson's numerical renormalization group (NRG) approach for quantum impurity systems. The NRG is particularly well suited to accurately solve problems which show infrared divergencies in a perturbative expansion. The analysis of the renormalization group fixed points yields a deep physical inside and the energy scales covering the crossovers between the fixed points. I will discuss the complete basis set of the Wilson chain which is an approximate eigen-basis of the Hamiltonian. This basis set of all (by the NRG procedure) discarded states lies at the heart of the recently developed extension of the NRG to non-equilibrium. I will show how to access real-time dynamics to investigate local spin and charge evolution using the time-dependent NRG. A recently proposed approach to Green`s functions will be discussed. It also makes explicit use of the complete NRG basis set which ensures a sum-rule conserving spectral function.