ELSEVIER Physica B 199&200 (1994) 341-343 Dynamical effect corrections to hole in CuO2 planes self-energies G. Martinez a'*, J.R. Iglesias ~, E.V. Andz b "lnstituto de Fisica, Universidade Federal do Rio Grande do Sul, 91500 Porto Alegre, RS, Brasil blnstituro de Fisica, Universidade Federal Fluminense. 24020 Niterbi, RJ, Brasil Abstract The total density of states for the three-band Hubbard model of CuO2 planes is calculated including fully self- consistent second-order perturbative corrections to the self-energy at the copper orbitais. We apply a configurationai mixing approach in a Bethe-lattice formulation to evaluate these quantum fluctuations in a local approximation. For realistic values of the model parameters we obtain a destruction of the antiferromagnetism at a small dopant hole concentration of 3-5 % due to the occurrence of a spin disordered state with local moments. The charge transfer gap is slightly reduced as compared with the Hartree-Fock result~ due to the incorporated dynamical effects. Since the discovery of high-temperature superconduc- tors [1], many studies were devoted to the analysis of the occurrence of this challenging phenomenon. It is by now clear that electronic correlations play a subsv.ntial role in these new materials, as is revealed by the richness of the magnetic phase diagram. Photoemission spectra as well as neutron diffraction experiments [2] have shown that the antiferromagnetic phase of the half-filled case is destroyed by a small hole doping concentration in the CuO2 planes, either induced by substitution with divalent atoms or by producing oxygen vacancies in compounds like Laz_xSrxCuO,_ r. The resulting phase ,.,~uld ~.,~n .... ;k~a " o v a spin or other spin disordered phase of exotic characteristics. Be- yond this critical doping concentration, the supercon- ducting phase occurs. In order to describe the normal- state properties of these strongly correlated systems, a three-band Hubbard model was proposed by Emery I-3-1. It consists mainly of a local description of the dx~_.~,~ * Corresponding author. copper orbitals and P0 oxygen orbitals, which are strong- ly hybridized in these compounds. Ad hoc Coulomb interactions are provided via Hubbard-like terms to treat the electron correlations properly. The Hamiltonian of this model reads, in short notation, H = ~.,~,cLc,s + Z t,jie',.cjs + h.c.~ is ij, s + ½Y'. Uin,sni-~. tl) is where ei = ca, e, and U, = Ua, Up for copper and oxy- gen sites, respectively. We consider a direct hopping t~j = tvd between nearest-neighbor oxygen and copper sites. Other interactions of the model are irrelevant for our discussion and were put equal to zero. In this work we use this model to describe the transition of the antiferromagnetic phase to the spin disordered dopant si uation q'he electronic Green's func- tions and the density of states were calculated with the Bethe-lattice method for a two-sublattice system. We considered a sel~'-consistent second-order pevlurbative 0921-4526/94/$07.00 '0 1994 Elsevier Science B.V. All rights reserved SSDI 0921-4526(93}EO305-Z