Nonlocal screening effects on core-level photoemission spectra investigated by large-cluster models

The copper 2p core-level x-ray photoemission spectrum in CuO2 plane systems is calculated by means of large-cluster models to investigate in detail the nonlocal screening effects, which were pointed out by van Veenendaal et al. [Phys. Rev. B 47, 11 462 (1993)]. Calculating the hole distributions for the initial and final states of photoemission, we show that the atomic coordination in a cluster strongly affects accessible final states. Accordingly, we point out that the interpretation for Cu3O10 given by van Veenendaal et al. is not always general. Moreover, it is shown that the spectrum can be remarkably affected by whether or not the O 2pπ orbits are taken into account in the calculations. We also introduce a Hartree-Fock approximation in order to treat much larger-cluster models.