1999 Fiscal Year Final Research Report Summary
Fluctuation and Functions of Liquid Water
| Project/Area Number |
10044074
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical chemistry
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| Research Institution | Nagoya University |
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Principal Investigator |
OHMINE Iwao Nagoya University, Chemistry Department, Professor, 大学院・理学研究科, 教授 (60146719)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUMOTO Masakazu Nagoya University, Research Center for Materials Science, Research Associate, 物質科学国際研究センター, 助手 (10283459)
SAITO Shinji Nagoya University, Chemistry Department, Associate Professor, 大学院・理学研究科, 助教授 (70262847)
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| Project Period (FY) |
1998 – 1999
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| Keywords | Water Dynamics / Fluctuation / Hydrogen Bond Network / Proton transfer / Solvation dynamics / Supercritical Water / Nonlinear Response / Freezing |
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| Research Abstract |
Various aspects of Water Dynamics have been investigated ; (1) Fluctuation and relaxation in hydrogen bond network rearrangement and its observation, (2) Proton transfer in liquid water and ice, (3) Solvation dynamics in supercritical water, and (4) Mechanism of water freezing.
(1) was investigated with normal mode analysis and MD calculation. We have found that there is no echo in 5th order nonlinear response in liquid state in general.
(2) (3) We have investigated the dynamic behavior of protons in liquid water and ice. Proton transfer in water is assisted by Hydrogen Bond Network Rearrangement (HBNR), making some water molecules three-coordinated. We also analyze the mechanism of the water molecule dissociation. There are two channels in the water molecular dissociation ; ion and radical channels. It is also found that in super-critical water the hydration is stronger than in water in spite of the fact that water molecular density is smaller, and hence the ionic channel becomes even more stable.
(4) We will also discuss the mechanism of water freezing. Having a potential energy surface (PES) of the 'fragile' characteristic [4] involving various deep energy minima, water is expected to be trapped at one of these local minima and form an amorphous structure upon cooling. To understand how water usually freezes to a crystalline structure, and how this pathway to a crystal bifurcates from those to amorphous ices, the global nature of the potential energy surface (GPES) of water must be analyzed. As a first step toward obtaining such knowledge, we examine GPES of water molecular clusters, related to how the hydrogen bond network changes with lowering energy. We then performed MD calculation on water freezing. It was found that crystalline suddenly takes place after certain induction-time. Various analyses were made to find how the hydrogen bond network grows in this freezing mechanism.
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