Vi. Belinicher et al., CONSISTENT LOW-ENERGY REDUCTION OF THE 3-BAND MODEL FOR ELECTRONS ANDHOLES IN COPPER OXIDES TO THE EFFECTIVE T-J MODEL, Physica. C, Superconductivity, 235, 1994, pp. 2183-2184
A full three-band model for the CuO2 plane with inclusion of all essen
tial interactions - Cu-O and O-O hopping, repulsion at the copper and
oxygen and between them - is considered. A general procedure of the lo
w-energy reduction of the primary Hamiltonian to the Hamiltonian for h
oles and electrons is developed. For the purpose of fixing of the t-J
model parameters we calculate the values of the superexchange constant
J and the charge-transfer gap E(gap) in the framework of the three-ba
nd model. Fitting values of J and E(gap) to the experimental data allo
ws to narrow the uncertainty region of the three-band model parameters
. As a result the ratio t/J of the t-J model is fixed in the range 2.4
divided by 2.7 for holes and 2.5 divided by 3.0 for electrons.