Theory of the Anderson impurity model: The Schrieffer{endash}Wolff transformation reexamined

Journal Article · Fri Nov 01 04:00:00 EST 1996 · Annals of Physics (New York)

DOI:https://doi.org/10.1006/aphy.1996.0123· OSTI ID:450167

Kehrein, S K; Mielke, A ^[1]

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1. Institut fuer Theoretische Physik, Ruprecht-Karls-Universitaet, D-69120 Heidelberg (Germany)

We test the method of infinitesimal unitary transformations recently introduced by Wegner on the Anderson single impurity model. It is demonstrated that infinitesimal unitary transformations in contrast to the Schrieffer{endash}Wolff transformation allow the construction of an effective Kondo Hamiltonian consistent with the established results in this well understood model. The main reason for this is the intrinsic energy scale separation of Wegner`s approach with respect to arbitrary energy differences coupled by matrix elements. This allows the construction of an effective Hamiltonian without facing a vanishing energy denominator problem. Similar energy denominator problems are troublesome in many models. Infinitesimal unitary transformations have the potential to provide a general framework for the systematic derivation of effective Hamiltonians without such problems. Copyright {copyright} 1996 Academic Press, Inc.

• OSTI ID: 450167
• Journal Information: Annals of Physics (New York), Journal Name: Annals of Physics (New York) Journal Issue: 1 Vol. 252; ISSN APNYA6; ISSN 0003-4916
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ANDERSON MODEL
ANTIFERROMAGNETISM
CRYSTAL MODELS
FERROMAGNETISM
HAMILTONIANS
KONDO EFFECT
RENORMALIZATION
SCALING LAWS
TRACE AMOUNTS