Potential energy curves of dioxygen anion species, O −2 and O 2−2

Abstract

The bondings and the potential energy curves of the ground states of the dioxygen anion species, O − 2( 2Π g) and O 2− 2( 1Σ + g) are studied by the single and double excitation configuration interaction (SD-CI) and the symmetry adapted cluster (SAC)/SAC-CI methods. For O − 2, the spectroscopic constants calculated by the SD-CI and SAC-CI methods are in reasonable agreement with experiment. For O 2− 2, we have found a metastable state in the potential curve, for which the SD-CI calculation gives an equilibrium distance of 1.64 Å and vibrational frequency of 615 cm −1, and the SAC/SAC-CI calculation gives 1.67 Å and 545 cm −1, respectively. The free O − 2 and O 2− 2 molecules are compared with the superoxide and peroxide species adsorbed on an Ag surface, respectively.