IONIZATION-POTENTIAL OF ALUMINUM CLUSTERS

Structure, electronic structure, and ionization potential of aluminum clusters of 2-23 atoms are studied with a total energy method based on the density-functional theory. The calculated adiabatic ionization po tentials agree remarkably well with the data from threshold photoioniz ation measurements. The analysis of results gives insight into hybridi zation effects in the smallest clusters as well as reveals certain clu sters that exhibit a clear jellium-type shell structure. An explanatio n of the experimental results in the size region of 12-23 atoms is giv en in terms of coexisting, competing icosahedral, decahedral, and fcc- based clusters.