First-principles calculations are used to study the effects that adsor
bate atoms (Li, Na, Mg, Al) have on the (001) surface of thin body-cen
tered-cubic Li films. The Li, Na, and Mg adsorbates induce a shallow h
ole on the surface of the substrate at the adsorption site. The Al ads
orbate, however, creates a low bump at the adsorption site. For the is
olated Li adsorbate the induced surface relaxation of the substrate ex
tends up to second neighbors from the adsorption site. The adsorbed Li
atom is able to push its way closer to the surface ii the number of a
tomic layers of the substrate sim is increased from 3 to 5. If the dis
tance between the two Li adsorbates is 3a (a=lattice parameter of the
substrate), both adsorbate atoms lie in their own, completely separate
, adsorption holes. When the distance between the adsorbates is decrea
sed to 2a, the adsorption holes are merged to form a common adsorption
valley.