  Results of recent density functional theory calculations for alkali metal
adsorbates on close-packed metal surfaces are discussed. Single adatoms on the
(111) surface of Al and Cu are studied with the self-consistent surface
Green-function method by which the pure adsorbate-substrate interaction may be
analyzed. Higher coverage ordered adlayers of K on Al(111), Na on Al(111), and
Na on Al(001) are treated using the <em>ab-initio</em> pseudopotential plane
wave method which affords the prediction of coverage dependent stable and
metastable adsorbate geometries and phase transitions of the adsorbate layers.
Together, these studies give insight and understanding into current key issues
in alkali metal adsorption, namely, the nature of the adsorbate-substrate bond
at low coverage and the occurrence of hitherto unanticipated adsorbate
geometries, and the associated electronic properties.
