Density Functional Study of Neutral and Charged Silver Clusters Agn with n = 2–22. Evolution of Properties and Structure

Geometries and electronic properties of neutral Agn, cationic Agn+, and anionic Agn– silver clusters with n = 2–22 were investigated by density functional theory (DFT) with M06 functional. For neutral clusters, transition from planar to “empty cage” structure occurs at n = 7, “empty cage” to “cage with one Ag atom” at n = 18, and to “cage with two Ag atoms” at n = 22. For lowest-energy Agn clusters, Ag8 and Ag18 show lowest polarizability due to closed-shell valence electron configurations 1S2/1P6 and 1S2/1P6/1D10. High stability of Ag8 is manifested in small dissociation energies of Ag9 to Ag8 plus Ag1 and Ag10 cluster to Ag8 plus Ag2. Cluster Ag20 with configuration 1S2/1P6/1D10/2S2 is stable due to low dissociation energy of Ag21 to Ag1 and Ag22 to Ag2. Cationic clusters with even n namely Ag10+ (9 valence electrons), Ag16+ (15 valence electrons), and Ag22+ (21 valence electrons) dissociate to Ag1 and closed-shell Ag9+ (1S2/1P6), Ag15+ (1S2/1D10/2S2) and Ag21+ (1S2/1P6/1D10/2S2). For odd n, Ag11+ and A...