The theoretical studies on struchtures and performances of Nin and NinAl(n=2-13)clusters
Transition metal clusters have become one of the most attractive areas of current research due to their very excellent performances on physical properties, chemical properties, magnetic and catalytic aspects, which originate from their unique geometrical structures.At present, it has attracted the attention of the researchers.Nickel clusters, one kind of the transition metal clusters, are widely used in catalytic reaction and magnetic materials because of their unique geometrical structures and delocalized d electrons.In recent years, studies on the experimental and theoretical aspects of nickel clusters and its alloy clusters are increasing day by day.This article calculates and analyzes the structures and performance of Nin and NinAl (n=2-13)clusters through the Density Functional Theory and Gaussian03 software, the main content and the results are as follows:(1)We calculate the binding energies, the magnetic moment and the ionization potential of nickel clusters through various methods of the Gaussian03 program and then analyze on the basis of the experimental data and other methods reported in the previous literatures.Theoretical results show that BPW91/Lanl2dz is the best level for nickel clusters research.The ground state configurations and electronic structure properties of Nin (n=2-13) clusters are investigated in the BPW91/Lanl2dz level of DFT method and explain the paramagnetic and diamagnetic to the influence of the magnetic moment after different nickel cluster molecular hybridization by the molecular orbital diagram.(2) We make the ground state configurations ofNinAl (n =1-8, 12) clusters in BPW91/Lanl2dz/6-31G(d) level and find that Al atom adsorb in lateral of nickel clusters priority.The adsorption model is point instead.In addition, we infer that NisAl is the most stable cluster in NinAl (n=l to 8,12) clusters through the average binding energy and HOMO-LUMO gap analysis of doped clusters.The cluster is the most stable when the contents of Al is 16.7％ through analysizing the fragmentation energy, the second difference in energy and the ionization potential.The magneticmoment trend and the natural charge distribution of bimetallic clusters are agree with the molecular orbital diagram.Compared with monometallic nickel clusters, the magnetic moments of NinAl(n=l-8,12) clusters are reduced because of the diamagnetism of Al atom and s-p-d hybridization of Ni-Al.(3) We make the ground state configurations of NinAl-H2(n=l-6)clusters inBPW91/Lanl2dz/6-31G(d) level and find that hydrogen molecular adsorb in the edge of the cluster dissociativly.NBO analysis and Millikan charge analysis illustrate the internal orbit hybrid phenomenon of hydrogen adsorbed clusters: Electrons mainly transfer from 3s orbit of Al atom to 3d orbit of Ni atom and ls orbit of H atom.It can be seen from the parameters of chemical adsorption energy and the trend diagram that the chemical activity of Ni3Al-H2 cluster is strongest and Ni5Al-Hz cluster is most weak, respectively.To sum up, BPW91/Lanl2dz level is used for the first time to study the physical and chemical properties of Nin and 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.
密度泛函理论;镍团簇;几何结构;化学吸附
中国海洋大学
硕士
Matcrial physics and chemistry
Shou gangChen
2013
中文
O641
82
2013-12-31（万方平台首次上网日期，不代表论文的发表时间）