scholarly journals Wick's Theorem and a New Perturbation Theory around the Atomic Limit of Strongly Correlated Electron Systems

1994 ◽  
Vol 28 (3) ◽  
pp. 187-192 ◽  
Author(s):  
J Brinckmann
Keyword(s):  
Perturbation Theory ◽  
Strongly Correlated Electron Systems ◽  
Strongly Correlated ◽  
Electron Systems ◽  
Strongly Correlated Electron ◽  
Correlated Electron Systems ◽  
Correlated Electron ◽  
Atomic Limit ◽  
New Perturbation ◽  
Wick’S Theorem

scholarly journals RENORMALIZATION GROUP APPROACHES TO STRONGLY CORRELATED ELECTRON SYSTEMS

2001 ◽  
Vol 15 (19n20) ◽  
pp. 2549-2567 ◽  
Author(s):  
A. C. HEWSON ◽  
S. C. BRADLEY ◽  
R. BULLA ◽  
Y. ŌNO
Keyword(s):  
Perturbation Theory ◽  
Renormalization Group ◽  
Magnetic Impurity ◽  
Strongly Correlated Electron Systems ◽  
Strongly Correlated ◽  
Electron Systems ◽  
Strongly Correlated Electron ◽  
Correlated Electron Systems ◽  
Correlated Electron ◽  
Impurity Models

In recent years the numerical renormalization group (NRG) method has been extended to the calculation of dynamic response functions and transport properties of magnetic impurity models. The approach can now be applied more widely to lattice models of strongly correlated electron systems by the use of dynamical mean field theory (DMFT), in which the lattice problem is transformed into one for an effective impurity with an additional self-consistency constraint. We review these developments and assess the potential for further applications of this approach. We also discuss an alternative approach to renormalization, renormalized perturbation theory, in which the leading asymptotically exact results for the low temperature regime for a number of magnetic impurity models can be obtained within finite order perturbation theory.

EXACTNESS OF FERMIONIC LINEARIZATION SCHEME WITH CLIFFORD VARIABLES IN d=∞

1995 ◽  
Vol 09 (16) ◽  
pp. 971-975 ◽  
Author(s):  
ARIANNA MONTORSI
Keyword(s):  
Exact Solution ◽  
Single Site ◽  
Strongly Correlated Electron Systems ◽  
Strongly Correlated ◽  
Electron Systems ◽  
Strongly Correlated Electron ◽  
Correlated Electron Systems ◽  
Correlated Electron

We show that the fermionic linearization scheme for dealing with strongly correlated electron systems — when implemented with Clifford variables — becomes exact in the d=∞ limit, at least for Hubbard-like models. In this case, the model is mapped exactly into a single-site problem. The conditions under which such a feature allows to obtain an exact solution are also discussed.

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