The Stability And Magnetic Moments Of Fe_nO And Fe_nO₂Clusters: A Study Based On Density Function Theory

For understand the stability of clusters, peple researched the properties of the clusterwhich doped oxygen atoms, and find the discovery of the special nature of nano module. Ironas the3d transition metal representative, widely used in the industrial catalytic process, butiron clusters which contained oxygen atoms have widely used in the surface of catalytic andhigh density magnetic memory storage. Although there had so many research about ironclusters, such as C, N atoms, the characteristics of iron clusters which doped with the oxygenatom is not perfect. So we studied the oxygen atoms doped iron clusters.In order to research the characteristics of iron oxygen clusters, exchange and correlationsare treated within the generalized gradient approximation （GGA） of Perdew-Wang-1991（PW91） and Double-numerical basis plus polarized functions （DNP）. On the basis of the pureiron clusters, the most probable low-energy structures were found following an extensivesearch based on the low-energy structures of one or double oxygen atoms doped iron clusters.Through these methods, we have identified the ground state structures of Fe_nO（n=3-13）andFe_nO₂（n=2-11） clusters. Analysis of their structure stability, electronic structure andmagnetic properties have shown that:1. The growth pattern of Fe_nO（n=3-13） andFe_nO₂（n=2-11） clusters is amorphousforms, but the position of the doping oxygen atom is always in the surface of the clusters, inaddition to the oxygen atom of Fe₁₀Oclusters is located in the center of the clusters.2. Compared to the pure iron clusters, no matter a single or two oxygen atoms, themixed will improved the stability of the clusters. With the number of atoms increased thestability of the iron-oxygen clusters are increasing. The magic number clusters have greaterstability than neighboring clusters. By calculating the numerical second derivative of the binding energies of Fe_nO（n=3-13） clusters they show that: the Fe_nOcluster in n=5,8,10has local area peak, in other words Fe₅O, Fe₈O, Fe₁₀Oclusters are magic numberclusters in stability. As forFe_nO₂（n=2-11） clusters,Fe5O2andFe9O2clusters are magicnumber clusters. It is noteworthy that the oxygen atom in the Fe₁₀Ocluster is located in thecenter position of clusters, and the stability is the worst.3. Oxygen atom increases the overall energy gap of the Fe_nOclusters, it suggest thatthe chemical stability of the doped clusters have been enhanced. Doped with iron-oxygenclusters oxygen atoms have increased the total energy gap, the chemical stability of the dopedclusters show a decreasing trend with the increasing atomic number.4. According to the analysis of M ullikencharge, the oxygen atom negatively charged,the charge transfer direction is from the iron atoms to oxygen atoms. In the Fe_nOclusters,the total spin magnetic moments have a relationship with the oxygen atom charge transfer,within the scope of n>7, the more the charge transfer, the greater the magnetic moments.Within the scope of n<10, the magnetic moments ofFe_nO₂clusters has odd-evenoscillations, and still has an overall upward trend.