The electronic excitation spectra of Cs overlayers on Ag are calculated with use of the time-dependent density-functional approach. These spectra are found to undergo characteristic changes as the coverage increases from 0.5 to 2.0 monolayers. The nonlocal corrections to the Fresnel optics obtained from these spectra are in qualitative agreement with reflectivity measurements for p- and s-polarized light.

• Received 16 January 1990

DOI:https://doi.org/10.1103/PhysRevB.41.10463