Structure and atomic vibrations in bimetallic Ni$_{13-n}$Al$_n$ clusters

The binding energy, equilibrium geometry, and vibration frequencies in bimetallic clusters Ni$_{13-n}$Al$_n$ ($n=0$–$13$) have been calculated using the embedded atom method potentials. It has been shown that the icosahedral structure is the most stable in monoatomic and bimetallic clusters. A tendency of Al atoms to segregate on the cluster surface has been revealed in agreement with the experimental data. The calculations of the atomic vibrations have shown the nonmonotonic dependence of the minimum and maximum vibration frequencies of cluster atoms on its composition and the coupling of their extreme values with the most stable atomic configuration. The increase in the number of Al atoms leads to the shift of the frequency spectrum and the substantial redistribution of the localization of vibrations on the cluster atoms.