Theory of alkali adsorption on simple metal surfaces
1991; Elsevier BV; Volume: 242; Issue: 1-3 Linguagem: Inglês
10.1016/0039-6028(91)90290-9
ISSN1879-2758
Autores Tópico(s)Hydrogen Storage and Materials
ResumoThe electronic structure of alkali adlayers on metal surfaces is studied by first-principles calculations as a function of coverage (θ). Hexagonal Na layers with varying lattice constants are used as adlayers, and the substrate is represented by the semi-infinite jellium. The results obtained show that the classical Gurney model is insufficient to describe the Na-jellium bonding: despite the large potential lowering in the vacuum, the density of states in a Na sphere is rather insensitive to θ. The bonding-antibonding boundary regarding the Na-jellium bonding coincides with the Fermi level at the lowest θ, implying that the covalency in the Na-jellium bond becomes the largest at the lowest θ. The rapid decrease of the Na-induced dipole moment is caused mainly by the direct NaNa interaction due to the orbital overlap rather than by the indirect dipole interaction.
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