Accurate Predictions of Water Cluster Formation, (H2O)n=2-10
Accurate Predictions of Water Cluster Formation, (H2O)n=2-10
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DOI：
10.1021/jp104865w
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发表时间：
2010-11-04
影响因子：
2.9
通讯作者：
Shields, George C.
中科院分区：
文献类型：
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作者：
Shields, Robert M.;Temelso, Berhane;Shields, George C.
有效的混合分子动力学/量子力学模型已应用于水团簇系统。使用 MP2 方法和相关一致基组，并适当校正 BSSE，可以准确计算形成 2-10 个水分子簇的电子能和自由能。该方法揭示了 (H2O)(n=7,9,10) 的新低能构象异构体。水七聚体构象异构体包含五种不同的结构图案，从三维棱柱到准平面书结构。棱柱状结构在低温下受到大力青睐，但椅状结构是超过 200 K 的全局吉布斯自由能最小值。水九聚体表现出较低的复杂性，所有低能结构均呈棱柱状。该十聚体具有 30 个构象异构体，其范围在 298 K 时吉布斯自由能最小结构的 2 kcal/mol 范围内。这些结构分为四个构象异构体类别，五角柱是 0 至 320 K 范围内最稳定的结构。结果可用作经验水模型和密度泛函的基准值，并且该方法可应用于更大的水团簇。
An efficient mixed molecular dynamics/quantum mechanics model has been applied to the water cluster system. The use of the MP2 method and correlation consistent basis sets, with appropriate correction for BSSE, allows for the accurate calculation of electronic and free energies for the formation of clusters of 2-10 water molecules. This approach reveals new low energy conformers for (H2O)(n=7,9,10). The water heptamer conformers comprise five different structural motifs ranging from a three-dimensional prism to a quasi-planar book structure. A prism-like structure is favored energetically at low temperatures, but a chair-like structure is the global Gibbs free energy minimum past 200 K. The water nonamers exhibit less complexity with all the low energy structures shaped like a prism. The decamer has 30 conformers that are within 2 kcal/mol of the Gibbs free energy minimum structure at 298 K. These structures are categorized into four conformer classes, and a pentagonal prism is the most stable structure from 0 to 320 K. Results can be used as benchmark values for empirical water models and density functionals, and the method can be applied to larger water clusters.