SELF-CONSISTENT NUMERICAL STUDY OF PURE AND IMPURITY DOPED 3-BAND HUBBARD-MODEL

The three-band Hubbard model - both pure and with static non-magnetic impurities has been studied within a self-consistent numerical Hartree -Fock (HF) scheme. The system shows nesting properties only in the abs ence of direct O-O hopping. Spin excitations in the system are gapless with the existence of a Goldstone mode in the broken-symmetry state. The variation of spin-wave velocity with Cu-site Coulomb repulsion sho ws a (1/(2U(d))+(1/Delta)) dependence in the strong-coupling limit. Ea ch non-magnetic impurity in the system gives rise to two gap states fo r a particular spin and the local moment produced is robust even at fi nite concentration of mobile hole doping. The gapless Goldstone mode i s preserved even in case of unequal concentration of impurities on the two sublattices.