The effective Hamiltonian for copper oxides

The concentration dependence of the exchange integral for the subsystem of spin moments of copper ions J(h) = J ? J ₁ × h ? J ₂ × h ² has been calculated for the Emery model within the effective Hamiltonian obtained with due regard to intersite interactions and oxygen configurations with different numbers of holes. It is shown that allowance for the oxygen single-hole states occurring upon doping leads to additional contributions to J(h), whose intensities depend on the intersite correlations of the nearest environment of exchange-coupled copper ions.