Magnetic excitations of Co2 dimer

The electronic and geometrical structure of the ground and excited states of Co2 and Co2− has been calculated using the density functional theory with two generalized gradient approximations for the exchange-correlation potential. The computed electron affinity of Co2 (5Δg) is in good agreement with experiment. For each permitted spin multiplicity, Co2 possesses several states having close bond lengths and/or total energies. It is found that Co2 possesses an antiferromagnetic singlet state which is inaccessible by excitations from the triplet states but could be reached through magnetic de-excitations.