A benchmark study of dioxygen complexes based on coupled cluster and density functional theory

A set of five compounds containing peroxo, superoxo or bis-mu-oxo moieties has been studied in the gas phase using CCSD(T)/aug-cc-pVQZ, in combination with Goodson’s continued fraction approach. The corresponding analytical frequencies corroborate assignments of bands from experiments, and thus provide a consistent set of reference data that can be used for benchmarking a range of density functional approximations. A total of 75 density functionals have been checked for the bonds, peroxo/superoxo bonds, angles, vibrational frequencies and electronic energies. There is not one density functional that performs equally well for all of these properties, not even within one class of density functionals.