On the properties and atmospheric implication of amine-hydrated clusters
On the properties and atmospheric implication of amine-hydrated clusters
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胺水合团簇的性质及其对大气的影响
DOI：
10.1039/c5ra11462d
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发表时间：
2015-01-01
期刊：
影响因子：
3.9
通讯作者：
Huang, Wei
中科院分区：
文献类型：
--
作者：
Chen, Jiao;Jiang, Shuai;Huang, Wei
胺已被认为是形成新的大气颗粒物的重要前体物质。虽然在过去的几年中，二甲胺-水簇合物一直是大量理论研究的焦点，但关于这些簇合物的一些信息，如温度的影响，它们的弱相互作用的分析，以及它们的瑞利散射性质，仍然缺乏。本文采用密度泛函理论（PW 91 PW 91）和6-311++G（3df，3 pd）基组，系统地研究了（CH 3）（2）NH（H2O）（n）（n = 1-6）团簇的平衡几何结构和热力学性质.为了确定最稳定的异构体和不同异构体的顺序，使用两点外推法结合所有异构体的完整基组进行单点计算。优化的结构表明，第五个水分子的加入改变了最稳定的配置从准平面环结构的笼状配置。电子密度分析表明，配合物间的相互作用主要是中等氢键。测定了（CH_3）（2）NH（H_2 O）（n）（n = 1-6）团簇的构象布居和吉布斯自由能随温度的变化关系。（CH_3）（2）NH（H_2 O）（n）（n = 1-6）团簇的形成对温度的依赖性较弱。二甲胺-水簇合物在低温下是有利的，但这些簇合物可能难以形成，因为吉布斯自由能的小负值和二甲胺在各种大气条件下的相对浓度低的综合影响，这意味着二甲胺-水簇合物难以在大气中自发形成。最后，首次系统地研究了（CH_3）（2）NH（H_2 O）（n）（n = 1-6）体系的瑞利散射性质。
Amines have been recognized as important precursor species in the formation of new atmospheric particles. Although dimethylamine-water clusters have been the focus of a large number of theoretical studies during the last few years, some information regarding these clusters, such as the influence of temperature, the analysis of their weak interactions, and their Rayleigh scattering properties, is still lacking. In this study, the equilibrium geometric structures and thermodynamics of (CH3)(2)NH(H2O)(n) (n = 1-6) clusters were systematically investigated using density functional theory (PW91PW91) coupled with the 6-311++G(3df,3pd) basis set. To determine the most stable isomer and the order of the different isomers, single-point calculations were executed using a two-point extrapolation method in conjunction with the complete basis set for all isomers. The optimized structures show that the addition of a fifth water molecule changes the most stable configuration from a quasi-planar ring structure to a cage-like configuration. Electron density analysis shows that the interactions of these complexes are mainly medium hydrogen bonds. The dependence on temperature of the conformational population and the Gibbs free energies of the (CH3)(2)NH(H2O)(n) (n = 1-6) clusters were determined with respect to temperature (200-300 K). A weak dependence on temperature was found for the formation of (CH3)(2)NH(H2O)(n) (n = 1-6) clusters. Dimethylamine-water clusters are favorable at low temperatures, but these clusters may be difficult to form because of the combined effect of Gibbs free energies with small negative values and the low relative concentration of dimethylamine in various atmospheric conditions, and this implies that dimethylamine-water clusters are difficult to form spontaneously in the atmosphere. Finally, the Rayleigh scattering properties of (CH3)(2)NH(H2O)(n) (n = 1-6) have been investigated systematically for the first time.