New perturbation approach for inner-core photoelectron spectra of transition metals

Abstract

A new perturbation scheme for the photoelectron spectra of inner-core levels is developed using projection operators in order to investigate the core spectra of transition metals. The $d$-electron part is treated as a single-band Hubbard model. Both Coulomb and exchange interactions between the core electrons and the $d$ electrons are taken into account. The theory leads to the correct atomic limit and reproduces the edge singularity in the delocalized region. Numerical calculations are performed for the nonmagnetic $d$-electron state. The dependences of the spectra on the $d$ bandwidth, the exchange parameter, and the $d$-electron number are examined and compared with the recent theoretical work.