The generalized Kondo lattice model and its spin-polaron implementation for cuprates by projection method
It is shown that the spin-fermion model found to be an effective low-energy implementation of the three-band Emery model after Wannier transformation of $p_x$- and $p_y$-orbitals in the oxygen ions subsystem is reduced to the generalized Kondo lattice model. Its essential feature is the presence of spin-correlated hoppings of the current carriers between distant cells. Numerical calculations of the spin-polaron spectrum demonstrate the important role of the distant hoppings.