Isomerism and Structural Fluxionality in the Au-26 and Au-26(-) Nanoclusters

Using the minima hopping global optimization method at the density functional level, we found low-energy nanostructures for neutral Au-26 and its anion. The local-density and a generalized gradient approximation of the exchange correlation functional predict different nanoscale motifs. We found a vast number of isomers within a small energy range above the respective putative global minima with each method. Photoelectron spectroscopy of Au-26(-) under different experimental conditions revealed definitive evidence of the presence of multiple isomers, consistent with the theoretical predictions. Comparison between the experimental and simulated photoelectron spectra suggests that the photoelectron spectra of Au-26(-) contain a mixture of three isomers, all of which are low-symmetry core-shell-type nanoclusters with a single internal Au atom. We present a disconnectivity graph for Au-26(-) that has been computed completely at the density functional level. The transition states used to build this disconnectivity graph are complete enough to predict Au-26(-) to have a possible fluxional shell, which facilitates the understanding of Its catalytic activity.