Properties of Ammonium Ion-Water Clusters: Analyses of Structure Evolution, Noncovalent Interactions, and Temperature and Humidity Effects
Properties of Ammonium Ion-Water Clusters: Analyses of Structure Evolution, Noncovalent Interactions, and Temperature and Humidity Effects
复制标题
铵离子-水簇的性质：结构演化、非共价相互作用以及温度和湿度影响的分析
DOI：
10.1021/jp512323k
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发表时间：
2015
影响因子：
2.9
通讯作者：
W. Huang
中科院分区：
文献类型：
--
作者：
S.-T. Pei;S. Jiang;Y.-R. Liu;T. Huang;K.-M. Xu;H. Wen;Y.-P. Zhu;W. Huang
Although ammonium ion–water clusters are abundant in the biosphere, some information regarding these clusters, such as their growth route, the influence of temperature and humidity, and the concentrations of various hydrated clusters, is lacking. In this study, theoretical calculations are performed on ammonium ion–water clusters. These theoretical calculations are focused on determining the following characteristics: (1) the pattern of cluster growth; (2) the percentages of clusters of the same size at different temperatures and humidities; (3) the distributions of different isomers for the same size clusters at different temperatures; (4) the relative strengths of the noncovalent interactions for clusters of different sizes. The results suggest that the dipole moment may be very significant for the ammonium ion–water system, and some new stable isomers were found. The nucleation of ammonium ions and water molecules is favorable at low temperatures; thus, the clusters observed at high altitudes might not be present at low altitudes. High humidity can contribute to the formation of large ammonium ion–water clusters, whereas the formation of small clusters may be favorable under low-humidity conditions. The potential energy surfaces (PES) of these different sized clusters are complicated and differ according to the distribution of isomers at different temperatures. Some similar structures are observed between NH4+(H2O)nand M(H2O)n(where M represents an alkali metal ion or water molecule); whenn= 8, the clusters begin to form the closed-cage geometry. As the cluster size increases, these interactions become progressively weaker. The successive binding energy at the DF-MP2-F12/VDZ-F12 level is better than that at the PW91PW91/6-311++G(3df, 3pd) level and is consistent with the experimentally determined values.
