ELECTRONIC-STRUCTURE OF CU6, AG6, AU6, AND THEIR POSITIVE-IONS

The ground state energies of the group IB hexamer (Cu6, Ag6, and Au6) for four possible structural models, namely, 1A1 with a capped pentagonal structure (C5-upsilon), 1A1 with a tripyramidal structure (C2-upsilon), 1A1g with a circular ring structure (D6h), and 3T2g with an octahedral structure, as well as the positive ions, Cu61+, Ag6+, and Au6+ were computed using complete active space multiconfiguration self-consistent field followed by first, second order configuration interaction and multireference singles + doubles configuration interaction including d correlation methods. We considered excited states of Cu6+ also. The results indicated that the capped pentagonal structure is the most favorable structure in energy among the four structures for all three hexamers. The computed ionization potentials (IPs) of Cu6, Ag6, and Au6 follow the order IP (Au6) > IP (CU6) > IP (Ag6).