Evaluation of the two-particle propagator for the Hubbard model with the help of the Hubbard-I approximation

A. V. Rozhkov, A. L. Rakhmanov

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3 Citations (Scopus)

Abstract

The Hubbard-I approximation is generalized to allow for direct evaluation of the equal-time anomalous two-electron propagator for the Hubbard model on a two-dimensional square lattice. This propagator is compared against the quantum Monte Carlo data obtained by Aimi and Imada (2007 J. Phys. Soc. Japan 76 113708) in the limit of strong electron-electron interaction. The Hubbard-I predictions are in good qualitative agreement with the Monte Carlo results. In particular, d-wave correlations decay as cr-3 ('free-electron' behaviour) if the separation r exceeds 2-3 lattice constants. However, the Hubbard-I approximation underestimates the coefficient c by a factor of about 3. We conclude that the Hubbard-I approximation, despite its simplicity and artefacts, captures the qualitative behaviour of the two-particle propagator for the Hubbard model, at least for moderate values of r.

Original languageEnglish
Article number65601
JournalJournal of Physics Condensed Matter
Volume23
Issue number6
DOIs
Publication statusPublished - 16 Feb 2011
Externally publishedYes

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