  First-principles calculations of Cu(001) free-standing thin films have been
performed to investigate the oscillatory quantum size effects exhibited in
surface energy, work function, atomic relaxation, and adsorption energy of the
cesium adsorbate. The quantum well states have been shown and clarified at
particular $k$-points corresponding to the stationary extrema in bulk Brillouin
zone, which are in good agreement with experimental observations. The
calculated surface energetics and geometry relaxations are clearly featured by
quantum oscillations as a function of the film thickness of the film with
oscillation periods characterized by a superposition of long and short length
scales. Furthermore, we have investigated Cs adsorption onto Cu(001) thin films
as a function of the film thickness. Our systematic calculated results clearly
show the large-amplitude quantum oscillations in adsorption energetics, which
may be used to tailor catalysis, chemical reactions and other surface processes
in nanostructured materials.
