UNRESTRICTED HARTREE-FOCK APPROXIMATION OF THE EXTENDED EMERY MODEL

We use an unrestricted self-consistent Hartree-Fock approach to calcul ate the nature of doping states in the three-band Hubbard model. It tu rns out that for physically relevant parameter values one hole is loca lized within a small spin-polarized region where five Cu spins are ali gned in the same direction. The spin polarization and binding energy b etween these spin-polaronic states are investigated as a function of d ifferent parameters including a Holstein-type electron-phonon coupling on the Cu sites. At higher doping concentration we observe the occurr ence of afmon states where the holes are localized in a ring-shaped ar ea. Inside this ring the antiferromagnetic order parameter has inverse sign with respect to the residual antiferromagnetically ordered plane .