| speaker: | Kevin Ingersent Gainesville, USA |
| time: | We., 15.08, 11:00-12:00 |
There is current interest in a range of nontrivial quantum impurity problems in which a local dynamical degree of freedom is coupled to bosons. Examples include magnetic impurity systems with electron-phonon interactions, molecular devices with vibrational motion, quantum dots subjected to various dissipative mechanisms, and the treatment of strongly correlated lattice systems within extended dynamical mean-field theory. This talk will review the progress made by several research groups towards incorporating bosons into the numerical renormalization group method, which for more than 30 years has provided reliable, nonperturbative solutions to pure-fermionic impurity problems. Methods will be described for treating three classes of problems of increasing computational complexity: (1) an impurity interacting with a local boson mode as well as with a fermionic band; (2) models involving dispersive bosons but no fermions; and (3) an impurity coupled both to dispersive bosons and to delocalized fermions. Strengths and limitations of these methods will be discussed.