Hole pairing within an extended Anderson impurity model applicable to the high-Tccuprates

We calculate the binding energy of a hole pair within the extended Anderson Hamiltonian for the high-$T_c$ cuprates including a Cu impurity and an oxygen-derived band. The results indicate that stable hole pairs can be formed for intra-atomic and interatomic Coulomb repulsion strengths larger than 6 and 3.5 eV, respectively. It is also shown that the total hybridization strength between the Cu $3d$ and oxygen $p$ band should be less than 2.5 eV. The hole pairing takes place primarily within the oxygen-derived $p$ band. The range of parameter values for which hole pairing occurs is also consistent with the earlier photoemission results from these cuprates.