Geometries and electronic properties of NamSin(m+n⩽7) clusters

The equilibrium geometries and electronic properties of NamSin(m+n⩽7) clusters have been studied by using density functional theory at the B3LYP/6-311+G(d) level. The ground state structures of NamSin clusters can be obtained by adding one Na atom to Nam-1Sin clusters, and the Na atom locates on the site which maximally tends to form NaSi bonds. The Si-rich clusters are more stable than Na-rich clusters with the same number of atoms. The SiSi bond is stronger than the NaSi bond, and the latter is stronger than the NaNa bond. The vertical ionization potentials of NamSin clusters obtained by B3LYP are in good agreement with the experimental values available. For such a certain cluster size (m+n=4,5,6,7), the energy gaps of the most stable NamSin clusters show odd-even oscillation with changing m, the clusters with odd Na atoms exhibit stronger chemical reactivity than those with even Na atoms.