L2,3absorption spectra of the lighter3dtransition metals

Abstract
A theory is presented for the x-ray absorption spectra of materials characterized by bandwidths which are somewhat larger than the (quasiatomic) electron correlation energies. Assuming that an empty-band approximation is appropriate for nearly empty bands we show that the problem is much akin to the well-known Coulomb localization problem in Auger spectroscopy, with an enhanced sensitivity for exchange and multipole effects because of the dipole selection rules. Using first-principles band structure and atomic data as input for the theory, we calculate the spectra of Ca, Ti, and V and obtain good agreement with high-resolution experimental spectra.