Role of electron distribution of H and D atoms in hydrogen bond

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We have performed four different works on the research project as follows :1. Neutron incoherent scattering experiments were performed to investigate the dynamical properties of hydrogen atoms in KDP.New model called phonon assisted incoherent tunneling was proposed based on the present experiments. We also try to investigate the electron distribution of hydrogen atom in KDP by X-ray diffraction, but reliable results are not obtained yet. The experiments are still being continued.2. Structure of low temperature phase of K_3D(SO_4)_2 was examined by a newly developed low temperature Weissenberg camera. We found that double q condensation occurs at V-point on the phase transition of K_3D(SO_4)_2. We also studied the successive phase transition of (NH_4)_3H(SO_4)_2. In this system, we found that not only V-point but also Z-point and GAMMA-point are relevant symmetry positions for the phase transition.3. New category materials as hydrogen bonded system were studied. One is a structural glass by hydrogen bonding, NH_4I-KI mixed system. Neutron incoherent scattering was performed to investigate the freezing of NH_4 ion motion. We also performed X-ray scattering experiments to look iodine motion. Another system is the intramolecular hydrogen bond system, d-BrHPLN.We found this system took commensurate-incommensurate transition.4. Technique to perform low temperature X-ray experiments, especially low temperature Weissenberg photograph, was developed. This technique opens the wide possibility to find weak satellite reflections in a reciprocal space.