Electronic structure analysis of small gold clusters Aum(m ≤ 16) by density functional theory

Small gold clusters Au m (m ≤ 16) were analyzed step by step using the density functional theory at B3LYP level with a Lanl2DZ pseudopotential to understand the rules governing the structures obtained for the most stable clusters. After a characterization by means of the NBO population analysis and spin densities, the particular electronic structure of such species was confronted to their structural parameters and stability. It appears that the most stable structures can be described in an original way through resonance structures resulting from an analysis of Au m clusters into dimeric Au2 subunits. These are arranged so as to promote: 1. A good overlap between bonding σ and anti-bonding σ* areas belonging to different Au2 units. 2. A cyclic flow of electrons over the whole cluster. This model uses relatively simple chemical concepts in order to justify most of the structures already found in the literature as well as to establish a new approach explaining the structural transition from two- to three-dimensional configuration