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

Abstract

The copper 2p core-level x-ray photoemission spectrum in ${\mathrm{CuO}}_2$ 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 ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{10}$ 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 2${\mathit{p}}_{\mathrm{\pi }}$ orbits are taken into account in the calculations. We also introduce a Hartree-Fock approximation in order to treat much larger-cluster models.