Functional-integral approach to strongly correlated Fermi systems: Quantum fluctuations beyond the Gutzwiller approximation

M. Lavagna
Phys. Rev. B 41, 142 – Published 1 January 1990
PDFExport Citation

Abstract

A systematic extension of the model of almost localized fermions to finite temperatures is presented. It consists in accounting for the quantum fluctuations beyond the Gutzwiller approximation (GA). We use the slave-boson formulation of the Hubbard model which has been proved to be equivalent at the saddle-point level to the GA. We determine the values of the Lagrange multipliers introduced to enforce the constraints, and show how they involve a Mott gap at nearly half filling for U>Uc (localization edge). The results of the GA for the correlation functions are reproduced at the saddle point when taking into account the implicit dependence of the boson fields with the external excitation. The Gaussian fluctuations are then considered in a renormalized basis of the boson fields which brings out two distinct channels (symmetric s and antisymmetric a). We show how the free energy and the correlation functions can be simply expressed as a function of the same Landau parameters F0s and F0a defined in the GA.

  • Received 7 July 1989

DOI:https://doi.org/10.1103/PhysRevB.41.142

©1990 American Physical Society

Authors & Affiliations

M. Lavagna

  • Institut Laue-Langevin, Boîte Postale 156X, 38042 Grenoble CEDEX, France

References (Subscription Required)

Click to Expand
Issue

Vol. 41, Iss. 1 — 1 January 1990

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review B

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×