The magic gold cluster AU(20)

The 20-nanogold cluster Au-20 exhibits a large variety of two- and three-dimensional isomeric forms. Among them is the ground-state isomer Au-20(T-d) representing the stable cluster with a unique tetrahedral shape, with all atoms on the surface, and large HOMO-LUMO gap which even slightly exceeds that of the buckyball fullerene C-60. The anionic cluster Au-20(-) (T-d) that holds its parent tetrahedral symmetry features a high catalytic activity. The list of the properties of the 20-nanogold clusters surveyed in the present work ranges from the energetic order of stability of its isomers to the optical absorption and excitation spectra of the Au-20(T-d) cluster. We also report the structures and properties of its doubly charged clusters Au-20(2+) and Au-20(2-) and computationally confirm that Au-20 is indeed stable. The zero-point-energy-corrected adiabatic second electron affinity of Au-20(T-d) amounts to 0.43-0.53 eV that is consistent with the experimental data. In addition, we provide computational evidence of the existence of the novel, hollow cage isomer of Au-20 and analyze its key properties. (C) 2007 Wiley Periodicals, Inc.