Structural transitions in metal clusters
Structural transitions in metal clusters
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金属团簇的结构转变
DOI：
10.1039/fd9919200217
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发表时间：
1991
影响因子：
3.4
通讯作者：
D. Sullivan
中科院分区：
文献类型：
--
作者：
J. Bernholc;J. Yi;D. Sullivan
团簇结构和动力学的第一性原理计算方法已经发展到可以计算含钙原子团簇的程度。可以研究50个非过渡金属原子。作为一个范例，我们研究了13和55原子铝团簇，可以假设完美的二十面体和立方八面体结构的结构转变的能量。利用Car-Parrinello（量子分子动力学）理论，我们发现Al 13具有一个独特的结构，一个轻微扭曲的二十面体，而Al 55具有几个不等价但能量上接近简并的结构。Al 55中的简并是由于金属团簇中有效原子间相互作用的范围较短，并且在有限温度下应导致松弛。在Car-Parrinello理论框架下，发展了一种新的精确计算电离势（Ei）和电子亲合势（Eea）的方法，并应用于Al团簇。不幸的是，似乎至少对于某些簇，最明显的是对于Al 55，Ei和Eea对于该簇的不同结构模型非常相似。简要介绍了一种新的基于多重网格的真实的空间电子结构计算方法的公式和首次试验。在不久的将来，这种方法应该可以对含有过渡金属和/或第一行原子的团簇进行类似于上述的计算。
The methods for first-principles calculation of the structure and dynamics of clusters have now progressed to a point where clusters containing ca. 50 non-transition-metal atoms can be studied. As a paradigm, we studied the energetics of structural transformations in 13- and 55-atom Al clusters, which can assume both perfect icosahedral and cuboctahedral structures. Using the Car–Parrinello (quantum molecular dynamics) formalism, we found Al13 has a unique structure, a slightly distorted icosahedron, but Al55 has several inequivalent but energetically nearly degenerate structures. The degeneracy in Al55 is due to the short range of the effective interatomic interactions in a metallic cluster and should lead to floppiness at finite temperatures. A new accurate procedure for calculating ionization potentials (Ei) and electron affinities (Eea) within the Car–Parrinello formalism was developed and applied to Al clusters. Unfortunately, it appears that at least for some clusters, most notably for Al55, the Ei and Eea are very similar for different structural models of this cluster. A formulation and the first tests of a new multigrid-based method for real space electronic structure calculations are briefly described. This method should make possible calculations similar to the above for clusters containing transition metal and/or first-row atoms in the fairly near future.