Ge adsorption on Ag(111): A density-functional theory investigation

First-principles density-functional theory has been used to investigate the adsorptions of Ge on Ag(111) surfaces for a wide range of coverage. Preferred adsorption sites, adsorption energies, surface structures, and the electronic properties are studied. Our results show that adsorption on the surface in fcc- sites is energetically favorable. The adsorption energies decrease as increasing Ge atoms, while the work functions of Ag surface decrease. The contour maps of the difference charge show that there exists covalent bonding in lower coverage systems to some extent for Ge on Ag(111) surface, and the interaction of Ge and Ag atoms becomes weaker with the increase of adsorption degree. The calculated density of states indicates that the adsorption structures have metallic character, while the number of electron transition is small and the interaction is not strong between Ge and Ag atoms.

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