Limitations in the structural determination of a close-packed overlayer

The close-packed metal overlayer system c(10 x 2)Ag/Cu(001) has been the subject of extensive electronic structure studies. These include the examination of the two-dimensional behavior at low coverages, the development from two- to three-dimensionality, and the convergence to three-dimensional dispersion as in Ag(111). It would be of use to have a firmer picture of the placement of the first monolayer Ag atoms (d) versus the Cu(001) substrate. However, it will be demonstrated with FEFF that there are fundamental limitations to the extraction of that information with photon-induced electron diffraction.