The Theoretical Studies On Structures And Performances Of Ni_n And Ni_nAl (n=2-13)Clusters

Transition metal clusters have become one of the most attractive areas of currentresearch due to their very excellent performances on physical properties, chemicalproperties, magnetic and catalytic aspects, which originate from their uniquegeometrical structures. At present, it has attracted the attention of the researchers.Nickel clusters, one kind of the transition metal clusters, are widely used in catalyticreaction and magnetic materials because of their unique geometrical structures anddelocalized d electrons. In recent years, studies on the experimental and theoreticalaspects of nickel clusters and its alloy clusters are increasing day by day.This article calculates and analyzes the structures and performance of NinandNinAl (n=2-13)clusters through the Density Functional Theory and Gaussian03software, the main content and the results are as follows:(1)We calculate the binding energies, the magnetic moment and the ionizationpotential of nickel clusters through various methods of the Gaussian03program andthen analyze on the basis of the experimental data and other methods reported in theprevious literatures. Theoretical results show that BPW91/Lanl2dz is the best level fornickel clusters research. The ground state configurations and electronic structureproperties of Nin(n=2-13) clusters are investigated in the BPW91/Lanl2dz level ofDFT method and explain the paramagnetic and diamagnetic to the influence of themagnetic moment after different nickel cluster molecular hybridization by themolecular orbital diagram.(2) We make the ground state configurations of NinAl (n=1-8,12) clusters inBPW91/Lanl2dz/6-31G(d) level and find that Al atom adsorbs in lateral of nickelclusters priority. The adsorption model is pointed instead. In addition, we infer thatNi5Al is the most stable cluster in NinAl n=1to8,12clusters through the averagebinding energy and HOMO–LUMO gap analysis of doped clusters. The cluster is the most stable when the contents of Al is16.7%through analysizing the fragmentationenergy, the second difference in energy and the ionization potential. The magneticmoment trend and the natural charge distribution of bimetallic clusters are agree withthe molecular orbital diagram. Compared with monometallic nickel clusters, themagnetic moments of NinAl(n=1-8,12) clusters are reduced because of thediamagnetism of Al atom and s-p-d hybridization of Ni-Al.(3) We make the ground state configurations of NinAl-H2(n=1-6)clusters inBPW91/Lanl2dz/6-31G(d) level and find that hydrogen molecule adsorb in the edgeof the cluster dissociativly. NBO analysis and Millikan charge analysis illustrate theinternal orbit hybrid phenomenon of hydrogen adsorbed clusters: Electrons mainlytransfer from3s orbit of Al atom to3d orbit of Ni atom and1s orbit of H atom. It canbe seen from the parameters of chemical adsorption energy and the trend diagram thatthe chemical activity of Ni3Al-H2cluster is strongest and Ni5Al-H2cluster is mostweak, respectively.To sum up, BPW91/Lanl2dz level is used for the first time to study the physicaland chemical properties of Ninand NinAl (n=2-13) clusters. The accuracy of the levelhas important reference significance for nickel clusters research and provides a certaintheoretical basis for seeking new functional materials in the future.