Department of Chemistry, University of Washington, Seattle, Washington 98195, United States.
Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States.
J Phys Chem Lett. 2023 May 25;14(20):4666-4672. doi: 10.1021/acs.jpclett.3c00952. Epub 2023 May 11.
The isomerization pathway between the energetically low-lying Zundel and Eigen isomers of the protonated water hexamer was investigated using high-level calculations including a treatment of zero-point corrections. On the basis of these calculations, the Zundel-Eigen isomerization was found to proceed through a stable intermediate isomer, which consists of a four-membered ring with two single acceptor water molecules. The inclusion of vibrational zero-point energy is shown to be important for accurately establishing the relative energies of the three relevant isomers involved in the Zundel-Eigen isomerization. Diffusion Monte Carlo calculations including anharmonic vibrational effects show that all three isomers of H(HO) and D(DO) have well-defined structures. The energetic ordering of the three isomers changes upon deuteration. The implications of these results for the vibrational spectra of H(HO) and D(DO) are also discussed.
使用包括零点能修正在内的高精度计算，研究了质子化水六聚体中能量较低的 Zundel 和 Eigen 互变异构体之间的异构化途径。基于这些计算，发现 Zundel-Eigen 互变异构化是通过一个稳定的中间体进行的，该中间体由一个带有两个单接受水分子的四元环组成。振动零点能的包含对于准确确定 Zundel-Eigen 互变异构化中涉及的三个相关互变异构体的相对能量非常重要。包括非谐振动效应的扩散蒙特卡罗计算表明，H(HO)和 D(DO)的三种互变异构体都具有明确的结构。三种互变异构体的能量排序在氘化后发生变化。这些结果对 H(HO)和 D(DO)的振动光谱的影响也进行了讨论。
