Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University , Atlanta, Georgia 30322, United States.
J Am Chem Soc. 2017 Aug 16;139(32):10984-10987. doi: 10.1021/jacs.7b05459. Epub 2017 Aug 3.
The protonated water tetramer H(HO), often written as the Eigen cluster, HO(HO), plays a central role in studies of the hydrated proton. The cluster has been investigated spectroscopically both experimentally and theoretically with some differences and controversies. The major issue stems from the existence of higher-energy Zundel isomers of this cluster and the role these isomers might play in the IR spectra. Settling this fundamental issue is one goal of this Communication, where high-level quantum calculations of the IR spectra of the Eigen and three isomeric forms of this cluster are presented. These calculations make use of a many-body representation of the potential and dipole moment surfaces and VSCF/VCI calculations of vibrational eigenstates and the IR spectrum. The calculated spectra for the Eigen HO(HO) and DO(DO) isomers compare very well with experiment. The calculated spectra for the cis and trans-Zundel and ring isomers show prominent features that do not match with experiment but which can guide future experiments to search for these interesting and important isomers.
质子化的水四聚体 H(HO)，通常写作 Eigen 团簇，HO(HO)，在研究水合质子中起着核心作用。该团簇已经在实验和理论上进行了光谱研究，存在一些差异和争议。主要问题源于该团簇的高能 Zundel 异构体的存在，以及这些异构体在红外光谱中可能扮演的角色。解决这个基本问题是本通讯的一个目标，其中呈现了 Eigen 和这个团簇的三种异构形式的高水准量子计算红外光谱。这些计算利用了势能和偶极矩表面的多体表示，以及 VSCF/VCI 振动本征态和红外光谱的计算。Eigen 的 HO(HO)和 DO(DO)异构体的计算光谱与实验非常吻合。顺式和反式 Zundel 以及环异构体的计算光谱显示出与实验不匹配的显著特征，但可以指导未来的实验来寻找这些有趣和重要的异构体。
