Hydrogenation of 3d-metal oxide clusters: Effects on the structure and magnetic properties.

The geometrical structures and properties of the M8 O12 , M8 O12 H8 , and M8 O12 H12 clusters are explored using density functional theory with the generalized gradient approximation for all 3d-metals M from Sc to Zn. It is found that the geometries and total spin magnetic moments of the clusters depended strongly on the 3d-atom type and the hydrogenation extent. More than the half of all of the 30 clusters had singlet lowest total energy states, which could be described as either nonmagnetic or antiferromagnetic. Hydrogenation increases the total spin magnetic moments of the M8 O12 H12 clusters when MMnNi, which become larger by four Bohr magneton than those of the corresponding unary clusters M8 . Hydrogenation substantially affects such properties as polarizability, forbidden band gaps, and dipole moments. Collective superexchange where the local total spin magnetic moments of two atom squads are coupled antiparallel was observed in antiferromagnetic singlet states of Fe8 O12 H8 and Co8 O12 H8 , whereas the lowest total energy states of their neighbors Mn8 O12 H8 and Ni8 O12 H8 are ferrimagnetic and ferromagnetic, respectively. Hydrogenation leads to a decrease in the average binding energy per atom when moving across the 3d-metal atom series. © 2018 Wiley Periodicals, Inc.