Structures and relative stability of neutral gold clusters:: Aun (n=15-19)

We performed a global-minimum search for low-lying neutral clusters (Au-n) in the size range of n=15-19 by means of basin-hopping method coupled with density functional theory calculation. Leading candidates for the lowest-energy clusters are identified, including four for Au-15, two for Au-16, three for Au-17, five for Au-18, and one for Au-19. For Au-15 and Au-16 we find that the shell-like flat-cage structures dominate the population of low-lying clusters, while for Au-17 and Au-18 spherical-like hollow-cage structures dominate the low-lying population. The transition from flat-cage to hollow-cage structure is at Au-17 for neutral gold clusters, in contrast to the anion counterparts for which the structural transition is at Au-16(-) [S. Bulusu , Proc. Natl. Acad. Sci. U.S.A. 103, 8362 (2006)]. Moreover, the structural transition from hollow-cage to pyramidal structure occurs at Au-19. The lowest-energy hollow-cage structure of Au-17 (with C-2v point-group symmetry) shows distinct stability, either in neutral or in anionic form. The distinct stability of the hollow-cage Au-17 calls for the possibility of synthesizing highly stable core/shell bimetallic clusters M@Au-17 (M=group I metal elements). (c) 2006 American Institute of Physics.