ADSORBATE-ATOM-INDUCED RELAXATION OF THIN LI(001) FILMS

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.