Structural exploration of Au M^- (M = Si, Ge, Sn; x = 9-12) clusters with a revised genetic algorithm

We used a revised genetic algorithm (GA) to explore the potential energy surface (PES) of Au M^- (x = 9-12; M = Si, Ge, Sn) clusters. The most interesting finding in the structural study of Au Si^- (x = 9-12) is the 3D (Au₉Si^- and Au₁₀Si^-) → quasi-planar 2D (Au₁₁Si^- and Au₁₂Si^-) structural evolution of the Si-doped clusters, which reflects the competition of Au-Au interactions (forming a 2D structure) and Au-Si interactions (forming a 3D structure). The Au M^- (x = 9-12; M = Ge, Sn) clusters have quasi-planar structures, which suggests a lower tendency of sp³ hybridization and a similarity of electronic structure for the Ge or Sn atom. Au₉Si^- and Au₁₀Si^- have a 3D structure, which can be viewed as being built from Au₈Si^- and Au₉Si^- with an extra Au atom bonded to a terminal gold atom, respectively. In contrast, the quasi-planar structures of Au M^- (x = 9-12; M = Ge, Sn) reflect the domination of the Au-Au interactions. Including the spin-orbit (SO) effects is very important to calculate the simulated spectrum (structural fingerprint information) in order to obtain quantitative agreement between theoretical and future experimental PES spectra.