Water Dynamics; Fluctuation and Chemical Reactions

我们在《水动力学及其多样性》中讨论了以下五个问题：(1)常温和低温下的氢键网络重排动力学；低温水中有两种液体状态：低密度液体(LDL)和高密度液体(HDL)。我们进行了片断分析，以找出它们的氢键网络结构的性质。结果发现，大部分低密度脂蛋白的空隙中只有15种基本片段。还发现在片段之间存在非常强的结构约束；只有一对类型的片段可以附着到给定的片段上。这一事实解释了为什么低密度脂蛋白和高密度脂蛋白之间会存在相变。我们还展示了过冷态热容随温度的变化规律，揭示了其动力学关系和极化率的三维响应函数。(2)水结晶和熔化的分子机制；我们分析了…的形成碎片分析表明，在水冻结过程中，初始成核和成核过程较多。对冰的融化过程也进行了类似的分析。(3)非线性多维光谱的理论分析，特别是二维拉曼光谱的理论分析。我们对二维拉曼光谱进行了新的理论分析，以期揭示液体低频运动的本质。研究发现，该方法对动力学的非线性非常敏感，可以用来检测结构的规律性；例如，它可以检测极小的冰结构在水冻结过程中如何形成和生长的详细机制。(4)离子的水化结构。我们从理论上计算了水分子的自解离常数和温度依赖性，并成功地几乎完全再现了它的温度依赖性，得到了离子的水化结构。通过分析，我们发现了水化结构和相互作用的详细机理，以及在水化过程中如何发生远程电子转移。研究还发现，随着温度的升高，各离子离解能的稳定性增加。(这与常识相反。)我们找到了它的物理化学原因。这一发现与超临界水的高反应性有关。目前，我们一直在研究液体表面附近离子的水化结构。(5)蛋白质(生物聚合物)的反应动力学；光活性黄质子(PYP)的光循环和离子传输膜；我们在离子通道模型体系中研究了PYP的整体结构变化和离子传输机制。较少

We have addresses following five issues in " water dynamics and its diversity "(1) Hydrogen bond network rearrangement dynamics at normal and low temperatures ; There are two liquid states in low temperature water; low - density liquids (LDL) and high - density liquids (HDL). We have made a fragment analysis to find the nature of their hydrogen bond network structures. It is found that most of LDL space is covered with only 15 types of basic fragments. Also found is that there exists the very strong structural constrains among the fragments; only a couple type fragments can attach to a given fragment. This fact explains the reason why the phase transition can exist between LDL and HDL. We have also showed how frequency-dependent heat capacity changes in the super-cooled state with temperature, and revealed its relationship of dynamics and 3D - response function of polarizability.(2) Molecular mechanism for the crystallization and melting of water ; We have analyzed the formation of an … More initial nucleus and nucleation process in water freezing process by using fragment analysis. A similar analysis is applied for the melting process of ice.(3) Theoretical analysis of non-linear multi-dimensional spectroscopy, especially 2D - Raman Spectroscopy; We have made a new theoretical analysis on 2D- Raman Spectroscopy in order to find the nature of the low-frequency motions of liquids. It is found that this method is very sensitive to the nonlinearity of dynamics so that can be applied to detect the regularity of a structure; for example, it can detect the detail mechanism of how the very small ice structure is being built and grows in the process of water freezing.(4) Hydration structure of ions; We have made a calculation to estimate the auto-dissociation constant of water molecule and temperature dependence theoretically, and succeeded to reproduce its temperature dependence almost completely and obtain the hydration structure of the ions. From the analysis, we have found the detail mechanism of the hydration structure and the interaction, and how the long-range electron transfer takes place in this hydration process. Also found is that, when temperature rises, the stability of all energy of ionic dissociation ncreases. (This opposite to the common knowledge.) We found the physio-chemical reason for it. This finding is related to the high reactivity of supercritical water. Now, we have been investigating about hydration structure of ions near the surfaces of liquids.(5) Reaction dynamics of proteins (biological polymer) ; Light cycle of Photoactive Yellow Proton (PYP) and the ion transport membranes; We have investigate the overall structural change of PYP and the ionic transport mechanism in a ion channel model system. Less