Effects contributing to an observed expansion in the lattice constant of a Xe monolayer on Ag(111) relative to bulk Xe are calculated or estimated. The major effects are the differences in geometry for the lattice sums of the pair and triple-dipole potentials and the lateral interactions of monolayer adatoms through the substrate, which is treated as a continuum. The effects included account for approximately two-thirds of the observed expansion. Presumably the remaining one-third arises from forces depending on details of the electronic structure of the adatom-metal complex.
Bibliographical noteFunding Information:
* Work supported in part by the National Science Foundation Grants DMR 74-1197 and DMR 74-19826. ** Present address: Center of Materials Research, University of Maryland, College Park, Maryland 20742, USA