J. Luo et Ne. Bickers, SELF-CONSISTENT WEAK-COUPLING STUDY OF THE 3-BAND CUO2 MODEL, Physical review. B, Condensed matter, 47(18), 1993, pp. 12153-12166
The ''fluctuation-exchange'' approximation, a Baym-Kadanoff theory use
d previously to treat the one-band Hubbard model, is used to investiga
te a three-band model for the CuO2 planes in the cuprate superconducto
rs. Attention is restricted to (a) nearest-neighbor copper-oxygen hopp
ing and (b) a Hubbard-like Coulomb interaction on copper sites only. O
rbital-occupancy factors are shown to be in good agreement with previo
us quantum simulation studies. An instability eigenvalue analysis conf
irms that, as in the one-band model, the most likely channel for super
conductivity is a dx2-y2 singlet. The scale for onset of exponentially
long-ranged antiferromagnetic correlations is compared with results f
or the one-band model, and the role of hybridization in reducing the e
ffective Coulomb interaction is studied using a transformation to Wann
ier states.