Abstract
Abstract Water dynamical and thermodynamical properties in molecular scale were theoretically investigated in a wide range of temperatures to clarify the physical origin of anomalous water properties. It was found in water that there exist intermittent and collective motions that arise from hydrogen bond network rearrangement. These intermittent motions become more distinctive with temperature decrease and diminish at the glass transition. In a deeply supercooled region, water dynamics shows that a new (“the third”) branch exists in its relaxation and in this branch special defects, H2O1, play a critical role. These defects make water glass transition temperature remarkably low. The intermittent collective motions have significant effects on water phase transitions and chemical reactions. The detailed dynamical mechanisms of the water freezing and the ice melting processes were analyzed. It was found how the embryos of nuclei for these processes are created and grow. The fast proton transfer mechanism in ice was also investigated to find its physical origin. Due to a strong geometrical constraint in ice, the excess proton is not trapped in a deep energy minimum and makes a facile transfer on the small energy barrier surface. As for the auto-dissociation process of water molecules, non-monotonic temperature dependence was theoretically clarified in a wide range of temperatures from ambient to supercritical region. On water roles in biomolecular functions, ion/proton transports and concomitant molecular relaxations were examined in ion-channel, photoactive yellow protein and reaction center.
Published Version
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