Theoretical $2p$-core-level shift and crystal-field splitting at the Al(001) surface

Core-energy shifts and crystal-field splittings of the Al(001)-$2p$ levels are determined theoretically using our recently developed full-potential self-consistent linearized-augmented-plane-wave (FLAPW) method. From the electronic structure of a nine-layer Al(001) single slab, we find a $2p$-core-level shift of 120 meV to reduced binding energies for the surface and 50 meV for the subsurface layers and a crystal-field splitting of 38 meV for the $2p_{\frac{3}{2}}$ state in the surface layer. Thus these theoretical results emphasize that both effects are important for a proper analysis of experimental data.