中大機構典藏-NCU Institutional Repository-提供博碩士論文、考古題、期刊論文、研究計畫等下載:Item 987654321/53200
English  |  正體中文  |  简体中文  |  全文笔数/总笔数 : 66984/66984 (100%)
造访人次 : 23133570      在线人数 : 132
RC Version 7.0 © Powered By DSPACE, MIT. Enhanced by NTU Library IR team.
搜寻范围 查询小技巧:
  • 您可在西文检索词汇前后加上"双引号",以获取较精准的检索结果
  • 若欲以作者姓名搜寻,建议至进阶搜寻限定作者字段,可获得较完整数据
  • 进阶搜寻


    jsp.display-item.identifier=請使用永久網址來引用或連結此文件: http://ir.lib.ncu.edu.tw/handle/987654321/53200


    题名: 金銅合金金屬叢集(N=38)的磁性性質研究;Magnetism in 38-atom gold-copper clusters
    作者: 李凡尼;Agus Rifani
    贡献者: 物理研究所
    关键词: 金屬叢集;磁性;metallic cluster;Magnetic properties
    日期: 2012-05-10
    上传时间: 2012-06-15 20:27:22 (UTC+8)
    摘要: 我們使用第一原理的方法研究AunCu38-n.的結構和電子性質.首先,我們利用 [P. J. Hsu and S. K. Lai, J. Chem. Phys. 124, 044711 (2006)] 發展的演算法去找出合金叢集在溫度為零的最低能量結構.這個演算法使用的是Gupta勢能搭配基因演算法併能量谷跳躍法. 雖然此演算法的可信度在文獻被證實上非常高,但因為Gupta勢能是一個使用經驗法則得到近似方法,無法提供電子方面的性質.所以我們接著把上述得到的最低能量結構放到第一原理的軟體中作電子結構的後續計算.在電子結構部份,我們使用的方法為密度泛函理論,選用的是高斯型的基底組.結果發現初始結構因為加上了電子的影響會有構形上的扭曲變形. [P.J. Ballester and W.G. Richards, J. Comput. Chem. 28, 1711 (2007)] 發展出的超快構形識別技術可以幫助我們有效的區分出初始結構和因為電子所造成扭曲變形後的差異.這個差異反映並幫助我們理解電子在構形扭曲過程中所扮演的錯綜複雜角色.另外,電荷以及自旋電荷在叢集中的分佈以及自旋態密度的分析可以幫助我們理解並解釋某些叢集產生不尋常的淨磁矩發生的背後機制.此外,化學的分子點群理論成功的解釋某些高度對稱的結構產生淨磁矩的原因.We present first-principles theoretical calculations of the structural and electronic properties of bimetallic clusters AunCu38-n. For the former, we first appeal to the lowest energy configurations of AunCu38-n (for different n) that we determined previously from an accurate and reliable optimization algorithm [P. J. Hsu and S. K. Lai, J. Chem. Phys. 124, 044711 (2006)] which was used in conjunction with an empirical many-body potential, whereas for the latter we use a linear combination of Gaussian-type orbitals within the Kohn-Sham density functional theory. The above lowest energy structures are input as initial ionic configurations and employed in the spin unrestricted density functional theory calculations. A thorough comparison between the ionic structures obtained from the latter and those initial ones from the optimization algorithm is further effected by the ultra-fast shape recognition technique [P.J. Ballester and W.G. Richards, J. Comput. Chem. 28, 1711 (2007)] widely applied in chemistry for structural characterization. The disparity in cluster geometry between these two sets of ionic structures sheds light on the intricate role of valence electrons in their spatial distribution on the atomic sites in clusters. This information on charge and spin density dispersions together with spin-polarized density of states unveil the mystery of the net magnetic moments which are predicted uncommonly in some of the clusters of AunCu38-n. An explanation is offered of this unexpected magnetism in the context of the symmetry of ionic structures.
    显示于类别:[物理研究所] 博碩士論文

    文件中的档案:

    档案 描述 大小格式浏览次数
    index.html0KbHTML333检视/开启


    在NCUIR中所有的数据项都受到原著作权保护.

    社群 sharing

    ::: Copyright National Central University. | 國立中央大學圖書館版權所有 | 收藏本站 | 設為首頁 | 最佳瀏覽畫面: 1024*768 | 建站日期:8-24-2009 :::
    DSpace Software Copyright © 2002-2004  MIT &  Hewlett-Packard  /   Enhanced by   NTU Library IR team Copyright ©   - 回馈  - 隱私權政策聲明