Investigation of the hydrogen bonding in ice Ih by first-principles density function methods.
Investigation of the hydrogen bonding in ice Ih by first-principles density function methods.
复制标题
DOI：
10.1063/1.4736853
复制
发表时间：
2012-07
期刊：
影响因子：
--
通讯作者：
P. Zhang;L. Tian;Z. P. Zhang;G. Shao;Jichen Li
中科院分区：
文献类型：
--
作者：
P. Zhang;L. Tian;Z. P. Zhang;G. Shao;Jichen Li
用密度泛函理论（DFT）模拟冰的振动动力学是一项公认的困难任务，因此，即使是最简单的冰Ih的非弹性中子散射（INS）谱，特别是在400 cm（-1）以下的平动区，模拟的成功率也相当有限。其原因部分是由于水-水分子之间氢键（H-键）的复杂性质，这需要相当大的改进量子力学模拟方法，部分是由于冰结构中质子的随机性，这通常需要模拟大的超晶格。在这份报告中，我们提出了第一系列成功的模拟结果冰Ih DFT方法。基于DFT程序的最新进展，我们首次获得了理论结果，不仅再现了冰Ih在500 ~ 1200 cm（-1）之间的转动频率，而且再现了INS光谱平移区在240和320 cm（-1）处的两个光学峰[J. C. Li，J. Chem. Phys 105，6733（1996）]。此外，我们还研究了H（2）O分子的两两构型对氢键的影响，发现两两H（2）O在冰Ih晶格中的不同质子排列并不像早期的文章[J. C. Li和D. K. Ross，Nature（伦敦）365，327（1993）]，即，再现两个实验光学峰不需要调用两个H键，如在先前的模型中所提出的，这导致了相当大的争论。结果表明，所观察到的光学峰可能是由于H（2）O中H-O伸缩模的两个带之间的耦合。目前的计算工作有望揭示水的氢键的性质，并提供一种新的方法来探测水和生物材料之间的相互作用，其中氢键是必不可少的。
It is a well recognized difficult task to simulate the vibrational dynamics of ices using the density functional theory (DFT), and there has thus been rather limited success in modelling the inelastic neutron scattering (INS) spectra for even the simplest structure of ice, ice Ih, particularly in the translational region below 400 cm(-1). The reason is partly due to the complex nature of hydrogen bonding (H-bond) among water-water molecules which require considerable improvement of the quantum mechanical simulation methods, and partly owing to the randomness of protons in ice structures which often requires simulation of large super-lattices. In this report, we present the first series of successful simulation results for ice Ih using DFT methods. On the basis of the recent advancement in the DFT programs, we have achieved for the first time theoretical outcomes that not only reproduce the rotational frequencies between 500 to 1200 cm(-1) for ice Ih, but also the two optic peaks at ∼240 and 320 cm(-1) in the translational region of the INS spectra [J. C. Li, J. Chem. Phys 105, 6733 (1996)]. Besides, we have also investigated the impact of pairwise configurations of H(2)O molecules on the H-bond and found that different proton arrangements of pairwise H(2)O in the ice Ih crystal lattice could not alter the nature of H-bond as significantly as suggested in an early paper [J. C. Li and D. K. Ross, Nature (London) 365, 327 (1993)], i.e., reproducing the two experimental optic peaks do not need to invoke the two H-bonds as proposed in the previous model which led to considerable debates. The results of this work suggest that the observed optic peaks may be attributed to the coupling between the two bands of H-O stretching modes in H(2)O. The current computational work is expected to shed new light on the nature of the H-bonds in water, and in addition to offer a new approach towards probing the interaction between water and biomaterials for which H-bond is essential.