title: Density and Phonon-Stiffness Anomalies of Water and Ice in the Full Temperature Range.
abstract: The specific-heat difference between the O:H van der Waals bond and the H-O polar-covalent bond and the Coulomb repulsion between electron pairs on adjacent oxygen atoms determine the angle-length-stiffness relaxation dynamics of the hydrogen bond (O:H-O), which is responsible for the density and phonon-stiffness oscillation of water ice over the full temperature range. Cooling shortens and stiffens the part of relatively lower specific-heat, and meanwhile lengthens and softens the other part of the O:H-O bond via repulsion. Length contraction/elongation of a specific part always stiffens/softens its corresponding phonon. In the liquid and in the solid phase, the O:H bond contracts more than the H-O elongates, hence, an O:H-O cooling contraction and the seemingly "regular" process of cooling densification take place. During freezing, the H-O contracts less than the O:H elongates, leading to an O:H-O elongation and volume expansion. At extremely low temperatures, the O:H-O angle stretching lowers the density slightly as the O:H and the H-O lengths change insignificantly. In ice, the O-O distance is longer than it is in water, resulting in a lower density, so that ice floats.
authors.affiliation: Key Laboratory of Low-Dimensional Materials and Application Technologies (Ministry of Education) and Faculty of Materials, Optoelectronics and Physics, Xiangtan University , Hunan 411105, China.|NOVITAS, School of Electrical and Electronic Engineering, Nanyang Technological University , Singapore 639798.
authors.forename: Chang Q
authors.initials: CQ
authors.lastname: Sun
authors.affiliation: NOVITAS, School of Electrical and Electronic Engineering, Nanyang Technological University , Singapore 639798.|Center for Coordination Bond and Electronic Engineering, College of Materials Science and Engineering, China Jiliang University , Hangzhou 310018, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University , Beijing 100084, China.
authors.forename: Xiaojian
authors.initials: X
authors.lastname: Fu
authors.affiliation: School of Materials Science, Jilin University , Changchun 130012, China.
authors.forename: Weitao
authors.initials: W
authors.lastname: Zheng
authors.affiliation: Institute of Atomic and Molecular Sciences, Academia Sinica , Taipei 10617, Taiwan.
authors.forename: Jer-Lai
authors.initials: JL
authors.lastname: Kuo
authors.affiliation: Key Laboratory of Low-Dimensional Materials and Application Technologies (Ministry of Education) and Faculty of Materials, Optoelectronics and Physics, Xiangtan University , Hunan 411105, China.
authors.forename: Yichun
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: School of Physics, Nanyang Technological University , Singapore 639798.
authors.forename: Zexiang
authors.initials: Z
authors.lastname: Shen
authors.affiliation: State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University , Beijing 100084, China.
authors.forename: Ji
authors.initials: J
authors.lastname: Zhou
keywords: angle-length-stiffness relaxation dynamics; hydrogen bond; ice; phonon stiffness; water