COLLECTIVE ELECTRONIC EXCITATIONS AND THEIR DAMPING IN SMALL ALKALI CLUSTERS

We calculate collective electronic excitations and their damping in sm all Na(n) and Li(n) clusters. The ground state properties of these sys tems are described using the local density approximation, and the elec tronic excitations by the random phase approximation. The collective e xcitations in the first two closed-shell clusters with n = 2, 8 atoms are discussed in detail. We find that the coupling of electronic level s to vibrational degrees of freedom accounts quantitatively for the ob served width of the collective electronic excitations in alkali dimers . The origin of the analogous line broadening in Na8 is presently unre solved.