Structural aspects of the topological model of the hydrogen bond in water on auto-dissociation via proton transfer
Structural aspects of the topological model of the hydrogen bond in water on auto-dissociation via proton transfer
复制标题
水中氢键通过质子转移自动解离的拓扑模型的结构方面
DOI：
10.1039/c8cp02592d
复制
发表时间：
2018
影响因子：
3.3
通讯作者：
Garofalini, Stephen H.
中科院分区：
文献类型：
--
作者：
Lentz, Jesse;Garofalini, Stephen H.
分子动力学(MD)模拟被用来研究在大体积水中通过质子转移的氢键和自解离的结构和寿命，所使用的反应性和解离的全原子势已经被证明匹配各种水的性质和质子转移。使用拓扑模型，每个分子的供氢键和接受氢键相对于邻近水域上的其他氢键进行标记，描述了这些细节对水分子的结构、动力学和自电离的影响。与以前的数据一致，在低于100飞秒的时间尺度上观察到了不对称成键，以及线性、分叉和悬挂氢键的存在。氢键的寿命为2.1ps，与实验数据一致，具有飞秒量级的短时间振动。角关联函数、第二壳层水进入第一壳层的存在以及OH振动伸缩频率都与实验或从头计算一致。模拟显示，一小部分水分子在短时间内(飞秒)解离，然后快速复合。另一个氢键对受体和给体的作用在自解离分子间的质子转移中起着重要作用，这与局部(第一和第二壳层)水产生的强电场在引发解离中的作用是一致的。在模拟中，给体水的氢键数量为每个分子4.3个，这与之前关于产生增强解离的强大局部电场所需的氢键数量的数据一致。那些经历解离的分子的氢键的连续寿命自相关函数比所有没有质子转移的分子的连续寿命自相关函数要长得多。
Molecular dynamics (MD) simulations were used to investigate the structure and lifetimes of hydrogen bonds and auto dissociation via proton transfer in bulk water using a reactive and dissociative all-atom potential that has previously been shown to match a variety of water properties and proton transfer. Using the topological model, each molecule's donated and accepted hydrogen bonds were labeled relative to the other hydrogen bonds on neighboring waters, providing a description of the effect of these details on the structure, dynamics and autoionization of water molecules. In agreement with prior data, asymmetric bonding at the sub-100 femtosecond timescale is observed, as well as the existence of linear, bifurcated, and dangling hydrogen bonds. The lifetime of the H-bond, 2.1 ps, is consistent with experimental data, with short time librations on the order of femtoseconds. The angular correlation functions, the presence of a second shell water entering the first shell, and OH vibrational stretch frequencies were all consistent with experiment or ab initio calculations. The simulations show short-lived (femtoseconds) dissociation of a small fraction of water molecules followed by rapid recombination. The role of the other H-bonds to the acceptor and on the donor plays an important part in proton transfer between the molecules in auto dissociation and is consistent with the role of a strong electric field caused by local (first and second shell) waters on initiating dissociation. The number of H-bonds to the donor water is 4.3 per molecule in the simulations, consistent with previous data regarding the number of hydrogen bonds required to generate this strong local electric field that enhances dissociation. The continuous lifetime autocorrelation function of the H-bond for those molecules that experience dissociation is considerably longer than that for all molecules that show no proton transfer.