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

Abstract

We used a revised genetic algorithm (GA) to explore the potential energy surface (PES) of AuxM- (x = 9-12; M = Si, Ge, Sn) clusters. The most interesting finding in the structural study of AuxSi- (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 AuxM- (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 AuxM- (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.