Krones, Jörn2014-12-122014-12-122014http://hdl.handle.net/2003/3378510.17877/DE290R-6863The method of continuous unitary transformations (CUTs) is applied to the Anderson impurity and the Kondo model aiming at the systematic derivation of convergent e ective models. If CUTs are applied in a conventional way, diverging di erential equations occur. Similar to poor mans scaling the energy scale, below which the couplings diverge, corresponds to the Kondo temperature TK. We present a way to apply CUTs to the Kondo and to the Anderson impurity model so that no divergences occur but a converged e ective low-energy model is derived with small nite parameters at arbitrarily small energies. The ground state corresponds to a bound singlet with a binding energy given by the Kondo temperature TK.enContinuous unitary transformationsCUTFlow equationKondo effectKondo modelAnderson impurity modelEffective models530doctoral thesisSupraleitungKondo-Effekt