Belyanchikov M A, Zhukova E S, Tretiak S, Zhugayevych A, Dressel M, Uhlig F, Smiatek J, Fyta M, Thomas V G, Gorshunov B P
Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141700, Russia.
Phys Chem Chem Phys. 2017 Nov 22;19(45):30740-30748. doi: 10.1039/c7cp06472a.
Using quantum mechanical calculations within density functional theory, we provide a comprehensive analysis of infrared-active excitation of water molecules confined in nanocages of a beryl crystal lattice. We calculate infrared-active modes including the translational, librational, and mixed-type resonances of regular and heavy water molecules. The results are compared to the experimental spectra measured for the two principal polarizations of the electric field: parallel and perpendicular to the crystallographic c-axis. Good agreement is achieved between calculated and measured isotopic shifts of the normal modes. We analyze the vibrational modes in connection with the structural characteristics and arrangements of water molecules within the beryl crystal. Specific atomic displacements are assigned to each experimentally detected vibrational mode resolving the properties of nano-confined water on scales not accessible by experiments. Our results elucidate the applicability and efficiency of a combined experimental and computational approach for describing and an in-depth understanding of nano-confined water, and pave the way for future studies of more complex systems.
利用密度泛函理论中的量子力学计算，我们对局限于绿柱石晶格纳米笼中的水分子的红外活性激发进行了全面分析。我们计算了红外活性模式，包括普通水分子和重水分子的平动、摆动及混合型共振。将结果与针对电场的两个主要极化方向（平行和垂直于晶体学c轴）测量的实验光谱进行了比较。计算得到的和测量得到的简正模式的同位素位移之间取得了良好的一致性。我们结合绿柱石晶体中水分子的结构特征和排列来分析振动模式。为每个实验检测到的振动模式指定了特定的原子位移，从而解析了实验无法触及尺度上的纳米受限水的性质。我们的结果阐明了结合实验和计算方法来描述和深入理解纳米受限水的适用性和有效性，并为未来对更复杂系统的研究铺平了道路。
