
Andreas Mielke
Institut for Theoretical Physics
RuprechtKarls University
Philosophenweg 19
D69120 Heidelberg
Germany
Tel.: ++49 6221 549431 (Secretary)
Fax: ++49 6221 549331
email:
mielke@tphys.uniheidelberg.de
Stefan Kehrein, Andreas Mielke: Theory of the Anderson impurity model: The SchriefferWolff transformation reexamined
Ann. Physics (NY)252,
132
(1996)
.
AbstractWe apply the method of infinitesimal unitary transformations recently introduced by Wegner to the Anderson single impurity model. It is demonstrated that this method provides a good approximation scheme for all values of the onsite interaction $U$, it becomes exact for $U=0$. We are able to treat an arbitrary density of states, the only restriction being that the hybridization should not be the largest parameter in the system. Our approach constitutes a consistent framework to derive various results usually obtained by either perturbative renormalization in an expansion in the hybridization Anderson's 'poor man's' scaling approach or the SchriefferWolff unitary transformation. In contrast to the SchriefferWolff result we find the correct highenergy cutoff and avoid singularities in the induced couplings. An important characteristic of our method as compared to the 'poor man's' scaling approach is that we continuously decouple modes from the impurity that have a large energy difference from the impurity orbital energies. In the usual scaling approach this criterion is provided by the energy difference from the Fermi surface.
BibTeXentry
@article{Kehrein1996a,
author="Stefan Kehrein, Andreas Mielke",
title="Theory of the Anderson impurity model: The SchriefferWolff transformation reexamined",
journal="Ann. Physics (NY)",
volume="252",
pages="132",
year="1996"
}
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Last changes: 16.4.2018.
mielke@tphys.uniheidelberg.de
