Structural motifs of gold cluster anions with 17 to 69 atoms

Gold has very special bonding properties, which is mainly due to strong relativistic effects influencing its electronic system. Gold clusters therefore, exhibit a large variety of structures not seen for other metallic systems. However, a reliable identification of these structures, which usually is based on a comparison of simulated and measured spectra, has been difficult as calculations often could not reproduce the measurements even if the correct structural motif was assumed. Here we show that optimized DFT calculations can yield a close to perfect agreement between measured and simulated photoelectron spectra, which in combination with extensive structural searches permitted us to identify geometries of cluster anions with 17 to 69 atoms. Many of these turn out to be highly symmetric, demonstrating that the special bonding properties of gold do not favor amorphous structures. These results provide a basis for a more precise treatment of gold nanostructures.