GENERALIZED T-T'-J MODEL - PARAMETERS AND SINGLE-PARTICLE SPECTRUM FOR ELECTRONS AND HOLES IN COPPER OXIDES

A microscopically based Hamiltonian of the generalized t-t'-J model is presented. Two types of the additional t' terms are discussed. The nu merical range of the amplitudes corresponding to the additional t' ter ms for the real CuO2 planes is derived from the three-band model calcu lations. Using the variational spin-polaron approach the single-carrie r dispersions in the generalized t-t'-J model are calculated both for the hole- and electron-doped systems. The hole and electron band minim a are found to be at points (+/-pi/2,+/-pi/2), (0,+/-pi), and (+/-pi 0 ), respectively. The band minima shifts \Delta((0,pi)-(pi/2,pi/2))\ ar e not small (similar to J). The bandwidths for both cases of doping ar e found to be 1.5-4.0 times larger than those in the t-J model.