THEORETICAL-STUDY OF THE POSITIVE-IONS OF THE DIMERS AND TRIMERS OF THE GROUP-IB METALS (CU, AG, AND AU)

The molecular structure of the positive ions of the diatomic and triatomic systems containing the metals Cu, Ag, and Au are determined from ab initio calculations. The bond lengths of the positive diatomic ions are similar to those of the corresponding anions, because they all have a bond order of one half. The ionization potentials (IPs) of the homonuclear trimers are considerably smaller than those for either the atoms or diatomics, since the highest occupied molecular orbital is only weakly bonding. The neutral and positively charged trimers have comparable structures resulting in similar vertical and adiabatic IPs. The trends in the dimer and trimer IPs and atomization energies are explained by the fact that the IP of Au is larger than either Ag or Cu.