scholarly journals Proposal of a renormalization group transformation for lattice field theories

1994 ◽  
Vol 50 (9) ◽  
pp. 5935-5943 ◽  
Author(s):  
L. A. Fernández ◽  
A. Muñoz Sudupe ◽  
J. J. Ruiz-Lorenzo ◽  
A. Tarancón





1995 ◽  
Vol 42 (1-3) ◽  
pp. 802-804
Author(s):  
L.A. Fernández ◽  
A. Muñoz Sudupe ◽  
J.J. Ruiz-Lorenzo ◽  
A. Tarancón


This paper describes some properties of the eigenvalue equation ψ n +1 + ψ n -1 + 2α cos (2πβ n + ∆) ψ n = Eψ n . This is an example of the more general problem of a Hermitian eigenvalue equation in the form of a difference equation with periodic coefficients.These equations arise in solid state physics; they occur in connection with tight-binding models for electrons in one-dimensional solids with an incommensurate modulation of the structure, and in models for the energy bands of Bloch electrons moving in a plane with a perpendicular magnetic field. The model studied has a critical point when α = 1. Following some earlier work by Azbel (Azbel, M. Ya., Phys . Rev . Lett . 43, 1954 (1979)), an approximate renormalization group transformation is derived. This predicts that the spectrum and eigenstates have a remarkable recursive structure at the critical point, which is dependent on the expansion of β as a continued fraction. Also, when β is an irrational number, there is a localization transition from extended states to localized states as α increases through the critical point. This localization transition, which was previously discovered by Aubry & André (Aubry, S. & André, G. Ann. Israel phys . Soc . 3, 133 (1979)) using the Thouless formula for the localization length, is explained by the renormalization group transformation derived here.



1977 ◽  
Vol 20 (12) ◽  
pp. 431-434
Author(s):  
E. R. Caianiello ◽  
M. Fusco-Girard ◽  
M. Marinaro




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