MOLECULAR-DYNAMICS STUDY OF MELTING AND FREEZING OF SMALL LENNARD-JONES CLUSTERS
MOLECULAR-DYNAMICS STUDY OF MELTING AND FREEZING OF SMALL LENNARD-JONES CLUSTERS
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DOI：
10.1021/j100303a014
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发表时间：
1987-09-10
影响因子：
--
通讯作者：
ANDERSEN, HC
中科院分区：
文献类型：
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作者：
HONEYCUTT, JD;ANDERSEN, HC
用分子动力学模拟方法研究了Lennard-Jones原子小团簇的性质。发现含有13到147个原子的团簇经历了一个类似于块体材料的熔化转变，在低温下从低能的类固体结构转变为高温下的高能类液体结构。这种转变在团簇的平衡能随温度变化的曲线图上产生了明显的特征，但曲线的形状取决于团簇的大小，以及是否使用正则系综或微正则系综来计算性质。在有限速率下加热或冷却时，作为温度函数的非平衡能量可能与平衡结果显著不同。在一定的温度范围内，观察到了最低能结构、高能类液体结构以及典型的一个或多个中间结构之间的共存。对不同尺寸的FeE和二十面体结构的势能最小化结果表明，Lennard-Jones团簇必须至少包含5000个原子，其FeE结构才会比Mackay二十面体的结构更稳定。
The properties of small clusters of Lennard-Jones atoms were studied by using molecular dynamics simulations. Clusters containing from 13 to 147 atoms were found to undergo a transition, analogousto a melting transition for bulk materials, from a low-energy solidlike structure at low temperatures to a set of higherenergy liquidlike structuresat high temperatures. The transition creates noticeable features in plots of the equilibrium energy of clusters as a function of temperature, but the shapes of the curves depend on the size of the cluster and on whether a canonical ensemble or microcanonical ensemble is used for calculating the properties. The nonequilibrium energy as a function of temperature on heating or cooling at a finite rate can differ significantly from the equilibrium results. Coexistence among the minimum-energy structure, high-energy liquidlike structures, and typically one or more intermediate structures was observed over a range of temperatures. Results from potential energy minimization of fee andicosahedral structures of various sizes indicate that a Lennard-Jones cluster must contain at least 5000 atoms before the fee structure becomes more stable than the structureof the Mackay icosahedra.