Farrell James D, Wales David J
University Chemical Laboratories , Lensfield Road, Cambridge CB2 1EW, United Kingdom.
J Phys Chem A. 2014 Sep 4;118(35):7338-48. doi: 10.1021/jp4119666. Epub 2014 Mar 11.
Global optimization for molecular clusters can be significantly more difficult than for atomic clusters because of the coupling between orientational and translational degrees of freedom. A coarse-grained representation of the potential can reduce the complexity of this problem, while retaining the essential features of the intermolecular interactions. In this study, we use a basin-hopping algorithm to locate putative global minima for clusters of coarse-grained water molecules modeled using a monatomic water potential for cluster sizes 3 ≤ N ≤ 55. We characterize these structures and identify structural trends using ideas from graph theory. The agreement with atomistic results and experiment is rather patchy, which we attribute to the tetrahedral bias in the three-body potential that results in too few nearest neighbor contacts and premature emergence of bulk-like structure. In spite of this issue, the results offer further useful insight into the relationship between the structure of clusters and bulk phases, and the mathematical form of a widely used model potential.
由于取向自由度和平动自由度之间的耦合，分子团簇的全局优化可能比原子团簇困难得多。势能的粗粒化表示可以降低这个问题的复杂性，同时保留分子间相互作用的基本特征。在本研究中，我们使用盆地跳跃算法来定位粗粒化水分子团簇的假定全局最小值，这些团簇使用单原子水势进行建模，团簇大小为3≤N≤55。我们使用图论的思想来表征这些结构并识别结构趋势。与原子尺度结果和实验的一致性相当参差不齐，我们将其归因于三体势中的四面体偏差，这导致最近邻接触过少以及类体相结构过早出现。尽管存在这个问题，这些结果为团簇结构与体相之间的关系以及广泛使用的模型势的数学形式提供了进一步有用见解。
