Abstract
An attempt has been made to examine the bulk and surface properties of exciton bands near F
+, F and F
− centers (α, β and γ bands), diffusion of electron centers (F
+, F and F
−) and adsorptivity of atomic H over the undefected and defected (F
+, F and F
−) surfaces of LiH using an ab initio embedded cluster method at the Hartree–Fock approximation and Moller–Plesset second-order perturbation correction. The results confirm the exclusive dependence of the exciton bands on the type of the electron center. The activation energy for bulk diffusion increases monotonically in the series F
+→F→F
−. Bulk and surface relaxation effects are more important for F
+ than for F and F
− centers. The introduction of F or F
− center changes the nature of adsorption from physisorption to chemisorption. The introduction of F
− center changes the nature of LiH surface from an insulating surface to a semiconducting surface. As F and F
− centers are introduced, the HOMO and LUMO levels of the substrate shift to higher energies and the band gaps become narrower. These changes in the electronic structure make charge transfer between adsorbate and substrate energy levels and spin pairing with F center more facile in the course of adsorbate–substrate interactions.