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 numerical range of the amplitudes corresponding to the additional t' terms for the real CuO2 planes is derived from the three-band model calculations. Using the variational spin-polaron approach the single-carrier dispersions in the generalized t-t'-J model are calculated both for the hole- and electron-doped systems. The hole and electron band minima 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))\ are not small (similar to J). The bandwidths for both cases of doping are found to be 1.5-4.0 times larger than those in the t-J model.