Density functional study on size-dependent structures, stabilities, electronic and magnetic properties of AunM (M=Al and Si, n=1-9) clusters: comparison with pure gold clusters

The density functional theory (DFT) method has been employed to systematically investigate the geometrical structures, relative stabilities, and electronic and magnetic properties of Au (n) M (M = Al and Si, n = 1-9) clusters for clarifying the effect of Al (Si) modulation on the gold nanostructures. Of all the clusters studied, the most stable configurations adopt a three-dimensional structure for Au (n) Al at n = 4-8 and Au (n) Si at n = 3-9, while for pure gold systems, no three-dimensional lowest energy structures are obtained. Through a careful analysis of the fragmentation energy, second-order difference of energy, HOMO-LUMO energy gap, and magnetic moment as a function of cluster size, an odd-even alternative phenomenon has been observed. The results show that the clusters with even-number valence electrons have a higher relative stability, but lower magnetic moments. Furthermore, Al (Si) doping is found to enhance the stabilities of gold frameworks. In addition, the charge analysis has been given to understand the different effects of individual doped atom on electronic properties and compared further.