Self-consistent-field studies of core-level shifts in ionic crystals: LiF

Restricted-Hartree-Fock, self-consistent-field calculations have been performed for the ground and ionic states of clusters of lithium and fluorine atoms. These clusters are appropriately charged to represent an Li+F- ionic crystal and point charges are used to represent the Madelung field due to ions not explicitly included in the cluster. Factors giving rise to core- and valence-level binding-energy shifts have been examined and separated into compressional, relaxational, and effective Madelung contributions. Many tests of ionicity are shown to be well satisfied, although this is often caused by fortuitous cancellations. Extra-ionic relaxation energies on both the cation and anion are shown to be small, and shakeup probabilities are calculated. © 1984 The American Physical Society.