Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India.
J Chem Phys. 2017 Oct 28;147(16):164704. doi: 10.1063/1.4991594.
Structural and dynamical properties of interfacial water molecules near a hexagonal boron nitride sheet (h-BN) are investigated by means of Born-Oppenheimer molecular dynamics simulations. Orientational profiles in the interfacial regions reveal two distinct types of water molecules near the BN surface. Depending on the positions of the water molecules, on top of either N or B atoms, one type contains water molecules that are oriented with one OH bond pointing toward the N atoms and the other type contains water molecules that remain parallel to the BN sheet. Distinct hydrogen bonding and stabilization energies of these two types of water molecules are found from our calculations. In order to see the effects of dispersion interactions, simulations are performed with the BLYP (Becke-Lee-Yang-Parr) functional and also BLYP with Grimme's D3 corrections (BLYP-D3). An enhancement of water ordering near the surface is observed with the inclusion of dispersion corrections. Further analysis of the diffusion coefficients, rotational time correlation functions, and hydrogen bond dynamics shows that water molecules near the h-BN sheet move faster compared to bulk water molecules both translationally and rotationally. The water molecules in the first layer are found to show substantial lateral diffusion. The escape dynamics of water from the solvation layer at the BN surface is also looked at in the current study. We have also investigated some of the electronic properties of interfacial water such as the charge density and dipole moment. It is found that the water molecules at the surface of the BN sheet have a lower dipole moment than bulk molecules.
通过 Born-Oppenheimer 分子动力学模拟研究了六方氮化硼（h-BN）片附近界面水分子的结构和动力学性质。界面区域的取向分布揭示了 BN 表面附近两种不同类型的水分子。根据水分子的位置，在 N 或 B 原子的顶部，一种类型包含一个 OH 键指向 N 原子的水分子，另一种类型包含平行于 BN 片的水分子。从我们的计算中发现了这两种类型的水分子的氢键和稳定能的差异。为了观察色散相互作用的影响，使用 BLYP（Becke-Lee-Yang-Parr）泛函和带有 Grimme 的 D3 修正的 BLYP（BLYP-D3）进行了模拟。包含色散校正后，在表面附近观察到水分子的有序性增强。进一步分析扩散系数、旋转时间相关函数和氢键动力学表明，与体相水分子相比，h-BN 片附近的水分子在平移和旋转方面移动得更快。发现第一层的水分子表现出显著的横向扩散。在当前的研究中还研究了水从 BN 表面的溶剂化层逸出的动力学。我们还研究了界面水分子的一些电子性质，如电荷密度和偶极矩。发现 BN 片表面的水分子的偶极矩比体相分子低。
