Ag_(309)团簇升温过程中结构转变的分子动力学模拟研究

The study of structural transformation for Ag_(309) clusters with molecular dynamics method

采用分子动力学模拟研究了具有面心立方(fcc)晶格结构的截断八面体Ag309团簇升温过程中结构演变.对团簇的能量曲线变化、快照图演变和键对分析表明:无缺陷截断八面体Ag309团簇在410K时转变为二十面体,在840K时熔化;不同缺陷诱导二十面体结构转变温度异常变化,沿晶面滑移缺陷使二十面体转变温度升高,沿晶面旋转缺陷使二十面体结构转变温度降低;不同缺陷对团簇键型和势能产生的影响是使二十面体结构转变温度异常变化的主要诱导因素.这种通过缺陷控制团簇结构转变的研究为新型纳米结构的可控制备提供理论基础.

The melting process of free and defect cuboctahedral Ag309 clusters has been studied by method of molecular dynamics.During the structure transformation from cuboctahedron to icosahedrals process,the variation of potential energy,the snapshots at different temperatures and the pair analysis technique are used.It is found that the cluster becomes into the icosahedral structure at 410 K and becomes into the liquid at 840 K for the free cuboctahedral Ag309 cluster.And the process of structural transformation from cuboctahedron to icosahedrals is influenced by defect,in which the temperature of structural transformation increases with slip defect,and decreases with screw defect.The different bond-types and potential energies of clusters play a key role for the icosahedrals transforming temperature.The irregular phenomenon during the melting is strongly related to the defect and gives an effective method to tune the novel nanomaterial.