Center for Superfunctional Materials, Department of Chemistry, Pohang University of Science and Technology , San 31, Hyojadong, Namgu, Pohang 790-784, Korea.
J Chem Theory Comput. 2011 Nov 8;7(11):3461-5. doi: 10.1021/ct200486c. Epub 2011 Oct 18.
Experimental vibrational predissociation spectra of the magic NH4(+)(H2O)20 clusters are close to those of the magic H3O(+)(H2O)20 clusters. It has been assumed that the geometric features of NH4(+)(H2O)20 clusters might be close to those of H3O(+)(H2O)20 clusters, in which H3O(+) resides on the surface. Car-Parrinello molecular dynamics simulations in conjunction with density functional theory calculations are performed to generate the infrared spectra of the magic NH4(+)(H2O)20 clusters. In comparison with the experimental vibrational predissociation spectra of NH4(+)(H2O)20, we find that NH4(+) is inside the cage structure of NH4(+)(H2O)20 as opposed to on the surface structure. This shows a clear distinction between the structures of NH4(+)(H2O)20 and H3O(+)(H2O)20 as well as between the hydration phenomena of NH4(+) and H3O(+).
实验振动预解离光谱的神奇 NH4(+)(H2O)20 团簇接近神奇 H3O(+)(H2O)20 团簇。人们认为 NH4(+)(H2O)20 团簇的几何特征可能接近 H3O(+)(H2O)20 团簇，其中 H3O(+)位于表面。Car-Parrinello 分子动力学模拟与密度泛函理论计算相结合，生成了神奇 NH4(+)(H2O)20 团簇的红外光谱。与 NH4(+)(H2O)20 的实验振动预解离光谱相比，我们发现 NH4(+)在 NH4(+)(H2O)20 的笼状结构内，而不是在表面结构上。这表明 NH4(+)(H2O)20 和 H3O(+)(H2O)20 的结构以及 NH4(+)和 H3O(+)的水合现象之间有明显的区别。
