Hole counts from X‐ray absorption spectra

The interpretation of X‐ray absorption spectra in terms of electronic structure has long been of interest. Hole counts derived from such spectra are often interpreted in terms of free‐atom occupation numbers or Mülliken counts. It is shown here, however, that renormalized‐atom (RA) and cellular counts are better choices to characterize the configuration of occupied electron states in molecules and condensed matter. A projection‐operator approach is introduced to subtract delocalized states and to determine quantitatively such hole counts from X‐ray absorption spectra. The described approach is based on multiple‐scattering theory (MST) and on atomic calculations of a smooth transformation relating the X‐ray absorption spectra to local projected densities of states (LDOS). Theoretical tests for the s and d electrons in transition metals show that the approach works well.