Condensed Matter Physics, 1996, No 8, p. 109-117, English
DOI:10.5488/CMP.8.109
Title: LOCAL PAIRING IN THE ATTRACTIVE HUBBARD MODEL
Authors: T.Di Matteo, F.Mancini, S.Marra
(INFM e Dipartimento di Fisica Teorica e S.M.S.A. Universita di Salerno , I-84140 Baronissi(SA), Italy)
The Hubbard model with on-site attractive interaction (negative-U Hubbard
model) is studied by means of the
composite operator method in the static approximation for the case of half
filling. At zero temperature, when the strength of the attractive interaction
equals the band width, the system exhibits a phase transition to a pair state,
where all the electrons are locally paired. The temperature T_p which
controls the cross over to the pair state is calculated as a function of
U. The double occupancy and the spin magnetic susceptibility
are calculated for various values of U and T. For strong attractive
interaction is strongly depressed, and tends to zero as T->T_P.
Comments:Refs. 9, Tabs. 0, Figs. 4.