Calculated Magnetic and Geometric Structures of Neutral Copper Oxide Clusters

The ground state geometric structures and electron configurations of sub-nanometer neutral copper oxide clusters are calculated with density functional theory. By comparing the results across almost forty clusters, ranging between Cu3O3 and Cu16O8, we find evidence for strong ferromagnetic coupling that is responsible for increasing the number of unpaired electrons as Cu atoms are in-cremented away from the (Cu2O)n stoichiometry. The closed shell (Cu2O)n clusters are nonmagnetic, whereas all other clusters ex-hibit a varying degree of magnetic susceptibility. The majority of the clusters considered in this manuscript have not been previous-ly evaluated. Natural bonding orbital analysis reveals a nearly linear correlation between the charge transfer between Cu and O at-oms and their local spin magnetic moments. Further, a relationship between the coordination of O atoms composing the cluster and their local magnetic moment is found. Bridging O atoms (μ2-O) typically exhibit large local magnetic moments, whereas the local magnetic moment is typically quenched in tetrahedrally coordinated (μ4-O) atoms. Thus, clusters containing CuI atoms contain a large total magnetic moment, whereas CuII atom clusters generally exhibit a small total magnetic moment and terminal Cu atom structures.