Multiple Scattering Approach to the XANES Theory of Alkali Halide Crystals

The conduction band structures of six alkali halide crystals (LiF, NaF, KF, LiCl, NaCl, KCl) are studied by means of the augmented plane wave method (APW). The local partial densities of states (LPDOS) and X-ray absorption K-spectra are calculated. The band structure predictions are compared with the results of cluster model calculations obtained within the framework of a Green's function approach employing multiple scattering technique. The effect of cluster size is examined for the clusters containing various numbers of atoms. It is shown that 57-atom clusters are sufficiently large to represent the band results in XANES region. The hole effect is exhibited as the intensity redistributions and the shifts of the peak positions, although more serious changes in the case of Li K-spectrum in LiF are found. [Russian Text Ignored].