Evolution of the electronic structure and properties of neutral and charged aluminum arsenide clusters: A comprehensive analysis

The B3LYP-DFT/6-311+G(d) method has been used to optimize the geometries of (AlAs)n neutrals and charged ions in the size range of n = 1–15. Frequency analyses are performed at the B3LYP/6-31G(d) level to check whether the optimized structures are transition states or true minima on the potential energy surfaces of corresponding clusters. The total energies of these clusters are then used to study the evolution of their binding energy, relative stability, and electronic properties as a function of size. The geometries are found to undergo a structural change from two-dimensional to three-dimensional when the cluster contains 6 atoms. The medium size clusters (n = 6–15) display the hollow globular conformers with large surface effect, which may cause the bulk limit still far from my computed results. The geometrical changes are companied by corresponding changes in the nearest-neighbor distances and coordination numbers. For medium size clusters (n = 6–15), both ionization potential and electron affinity have the tendency of decrease when the number of AlAs units in the cluster increases. Some magic clusters in neutral, cationic, and anionic form compared to its neighboring clusters are argued according to the calculated results of the second energy difference and electronic properties.