The correlation between the features of the geometric and electronic structures and the anion photoelectron spectra (PES) of AlnCsm- (n = 5-11; m = 1-3) were investigated using DFT calculations. The geometric changes from the octahedral to the wheel-like (or semi-icosahedral) structure were found in the n = 8 and 9 AlnCs clusters, and the n = 7 and 8 AlnCs2- and AlnCs3- clusters. The calculated vertical detachment energy (VDE) was in good agreement with the corresponding anion PES. The Kohn-Sham orbital energy gap of the 3p orbital region in the wheel-like structure was narrower than that in the octahedral structure. (C) 2010 Elsevier B.V. All rights reserved.