R. Putz et al., CONSERVING APPROXIMATION FOR THE 3-BAND HUBBARD-MODEL - FLAT QUASI-PARTICLE DISPERSION, Physical review. B, Condensed matter, 53(9), 1996, pp. 5133-5136
It is shown that the low-energy single-particle spectrum of the three-
band Hubbard model at finite hole dopings agrees remarkably well with
quantum Monte Carlo and experimental data within the framework of a co
nserving approximation including self-consistently the interaction wit
h charge, spin, and particle-particle fluctuations. The dispersion of
the quasiparticle peak is hat around the (pi,0), (0,pi) points as obse
rved in recent angle-resolved photoemission measurements. The signific
ant reduction of the dispersion near the Fermi level is due to spin fl
uctuations, rather than being induced by band effects.