Anion-radical oxygen centers in small (AgO)n clusters: Density functional theory predictions

► Oxygen centers of the (AgO)n (n = 1-4, 6) clusters are predicted to be anion-radical. ► The O/Ag ratio close to unity is responsible for the radicality of oxygen. ► The spins localized on oxygen are ferromagnetically ordered via nonmagnetic Ag bridges. ► The lowest excited states become antiferromagnetic. ► The O− center is suggested to be responsible for ethylene epoxidation on silver.