Theoretical study of geometry, stability and properties of Al and AlSi nanoclusters

Geometry, stability, and properties of Aln (n = 1–13) and AlnSim (n ? m = 5–7) nanoclusters were investigated by density functional theory. We found that while geometry of some clusters change significantly by substituting of Al atom(s) with Si atom(s) the geometry of some others remain without significant variation. The relative stability of clusters was discussed on the basis of binding energy per atom, fragmentation energy, and second- order difference of cluster energies. Our results reveal that Al7 is the most stable cluster among pure clusters. For AlnSim clusters, it is observed that Al2Si3 (60 % Si), and Al4Si2 (33.33 % Si) are the most stable clusters. The reactivity of Aln and AlnSim nanoclusters was also investigated on the basis of chemical hardness. The most important feature of chemical hardness is its oscillating behavior as a function of atomic percentage of Si indicating that the reactivity of AlnSim clusters strongly depends on the composition of cluster.