Effects of two-site composite excitations in the Hubbard model

2004/01/07 by Adolfo Avella, A. Avella, F. Mancini +2
Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #cond-mat.str-el

paper · pdf · doi:10.1016/j.jmmm.2003.12.1206

published as J. Magn. Magn. Mater. 272, E311 (2004) · 2 pages, 1 figure

arxiv created 2004/01/07 · openalex publication_date 2004/01/22 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

The electronic states of the Hubbard model are investigated by use of the Composite Operator Method. In addition to the Hubbard operators, two other operators related with two-site composite excitations are included in the basis. Within the present formulation, higher-order composite excitations are reduced to the chosen operatorial basis by means of a procedure preserving the particle-hole symmetry. The positive comparison with numerical simulations for the double occupancy indicates that such approximation improves over the two-pole approximation.

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• The 2-site Hubbard and t-J models

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