Ab Initio Study of Structure and Magnetism of Late Transition Metal Oxide TM_nO_m Clusters (TM = Fe, Co, Ni, n = 1, 2, m = 1-6)

摘要

We systematically investigate the structural and magnetic properties of late transition metal oxide clusters, TM_nO_m (TM = Fe, Co, Ni; n = 1, 2; m = 1-6) by using ab initio density functional theory approach. Fe_nO_m clusters prefer to adopt three dimensional configurations, while Co_nO_m and Ni_nO_m clusters are apt to form planar structures. The O atoms are all atomic bonding to Fe atoms in the Fe_nO_m clusters, and are partly molecularly adsorbed to Co(Ni) in Co_nO_m(Ni_nO_m) clusters, such as Co_2O_(5-6) (NiO_3, and Ni_2O_(4-6)). The average binding energies per atom of TM_nO_m show a monotonous increase trend with the increase of O atoms for both n = 1 and 2 for TM = Fe, Co and Ni, and reach the peak at m = 4 for TM_2O_m and decrease a little bit afterwards. The odd-even magnetic oscillation is major trait with the peaks at odd and bottoms at even sizes for Fe_2O_m and Ni_2O_m (m = 2-6), respectively and large magnetic moments are found in Co_2O_3 and Co_2O_6.