The adsorption of incommensurate monolayers on an hexagonal substrate: Lead underpotentially deposited on silver (111)

We discuss the incommensurate adsorption of an ad layer on a crystalline substrate. We show that in the case of Pb adsorbed on Ag(111) the size considerations are not enough to determine the angle of epitaxy: A special form of the adsorbing potential is required. The necessary conditions for this potential are discussed. An explicit form for the Pb/Ag(111) case is given.