Bonding in Cu, Ag, and Au clusters:: Relativistic effects, trends, and surprises -: art. no. 033401

Electronic structure and bonding in anionic coinage metal clusters are investigated via density-functional calculations, focusing on an extensive set of isomers of Cu-7(-) , Ag-7(-) , and Au-7(-) . While the ground states of Cu-7(-) and Ag-7(-) are three dimensional (3D), that of Au-7(-) is planar, separated from the optimal 3D isomer by 0.5 eV. The simulated thermally weighted photoabsorption spectrum of Au-7(-) is dominated by planar structures, and it agrees well with the measured one. The propensity of Au-N(-) clusters to favor planar structures (with N as large as 13) is correlated with strong hybridization of the atomic 5d and 6s orbitals due to relativistic effects.