Chemically induced changes in the magnetic moments in transition metal monomers and dimers

Self-consistent molecular orbital calculations based on the generalized gradient approximation to the density functional theory reveal that dinitrogen interacting with transition metal monomers and dimers can substantially alter their underlying spin multiplicity. In particular, the coupling between spins of two Cr atoms in Cr2 can change from anti-ferromagnetic to ferromagnetic with the atomic moment almost intact even when N2 is molecularly adsorbed. This effect, caused by the dilation of the metal–metal bond, can have an important impact in the study of magnetism in general.