Structural evolution of (Au2S)n (n = 1-8) clusters from first principles global optimizationElectronic supplementary information (ESI) available: AdNDP localized bonding patterns of (Au2S)n (n = 5-8) and atomic coordinates (in Å) of the global minimum structures. See DOI: 10.1039/c5ra06137g

• Main Authors: Feng, Yiqun, Cheng, Longjiu
• Format: Journal Article
• Language: English
• Published: 21.07.2015
• ISSN: 2046-2069
• DOI: 10.1039/c5ra06137g

We explore the structural evolution of (Au 2 S) n ( n = 1-8) clusters using a first principles global minimization technique, namely, a genetic algorithm from density functional theory geometry optimization (GA-DFT). The growth sequence and pattern for n from 1 to 8 are analyzed from the perspective of geometric shell formation. The average binding energy, HOMO-LUMO energy gaps, vertical electron affinity, and vertical ionization potential are examined as a function of the cluster size. The global minimum structures are planar at n = 1-3, three-dimensional at n = 4-8. The formation of these structures are attributed to the high stability of S-Au-S structural unit and particularly the Au 3 S 3 and Au 4 S 4 rings. Chemical bonding analysis reveals that the three-dimensional clusters ( n = 4-8) can be viewed as [Au 2 n − x S n ] x − · x Au + in electronic structure. The Au + cations are not involved in any S-Au covalent bond, however, are attracted by only Au Au aurophilic interactions. Direct evidence for the Au Au aurophilicity are given by a noncovalent interaction index analysis. Such Au Au aurophilic interactions play an important role in the stability of (Au 2 S) n clusters. First principles global optimization reveals the structural evolution and novel geometries of (Au 2 S) n nanoclusters at n = 1-8.