Abstract
We have recently developed a computational methodology to separate the effects of size, composition, symmetry and fluxionality in explaining the experimental photoelectron spectra of mixed-metal clusters. This methodology was successfully applied first in explaining the observed differences between the spectra of Al(13)(-) and Al(12)Ni(-) and more recently to explain the measured spectra of Al(n)Mo(-), n=3-5,7 clusters. The combination of our approach and new synthesis techniques can be used to prepare cluster-based materials with tunable properties. In this work we use the methodology to predict the spectrum of Al(6)Mo(-). This system was chosen because its neutral counterpart is a perfect octahedron and it is distorted to a D(3d) symmetry and was not observed in the recent experiments. This high symmetry cluster bridges the less symmetric Al(5)Mo(-) and Al(7)Mo(-)structures.The measured spectra of Al(5)Mo(-) has well defined peaks, while that of Al(7)Mo(-)does not. This can be explained by the fluxionality of Al(7)Mo(-), as at least 6 different structures lie within the range that can be reached by thermal effects. We predict that Al(6)Mo(-) has well defined peaks, but some broadening is expected as there are two low-lying isomers, one of D(3d) and the second of D(3h) symmetry that are only 0.052 eV apart.