Electronic Structure and Spectroscopy of the AuO + Cation.

The electronic structure and spectroscopy of the 29 lowest electronic states of the AuO + cation were studied using ab initio multiconfigurational methods. These states correlate to the Au + ( 1 S) + O( 3 P) and Au + ( 3 D) + O( 3 P) dissociation limits. Their potentials were calculated along the Au-O internuclear distance. There are 23 of these electronic states with potential wells deep enough to allow for long lifetimes of the AuO + cation in the corresponding states. These bound electronic states were characterized spectroscopically by solving the radial Schrödinger equation for the nuclear motion, to deduce full sets of spectroscopic parameters. The effects of the spin-orbit coupling on the lowest electronic states have been studied by determining the potentials and spectroscopic constants of the seven lowest spin-orbit Ω components. We also carried out precise calculations to determine the adiabatic ionization energy of the AuO molecule, where several corrections of the electronic energies obtained with the standard coupled cluster approach were taken into account. Our results will facilitate the correct assignment of the IR, vis, and UV spectra of the AuO + cation and the photoelectron spectrum of the neutral AuO diatomic.