1.1 What is “Structure” for Liquid Water?
3
(a)
(b)
Fig. 1.1 Pictures of two quasi-equilibrium configurations of N = 870 water molecules obtained by
minimizing the combination of Lennard-Jones and Coulomb interactions of pairs of TIP4P/2005model water molecules. a The structure of water. The thermal energy is higher than that allowed for
long-range order formation. b The structure of ice. The thermal energy is low enough for long-range
ordering. The local molecular environment stays nearly the same in both cases. Adapted from [2]
with permission from the PCCP Owner Societies
relatively large data acquisition time and cannot provide a true I-structure test. The
challenge of recent decades is to theorize an I-structure of water, the dynamics of
which would consistently give the V-, D-, and F-structures.
Some studies [4] show that there may be more than one meta-stable structure in
water and ice, which coexist in dynamic equilibrium. This concept has been found
useful for the explanation of neutron diffraction experiments [5], and gives a reason
to talk about the concept of low-density and high-density liquid states. Nevertheless,
a microscopic description of these two states is still lacking. It has recently been
shown that the combination of low-temperature ordered states of water based on
the tetrahedral structure and a high-temperature disordered state based on a distorted
tetrahedron structure can qualitatively explain some anomalies of water [6]. However,
the application of this approach for the explanation of the electrodynamic properties
of water is limited, mainly due to the lack of understanding on how and why these
two different water structures are formed, and change into each other.
1.2 Bragg Scattering and Bernal–Fowler Water
The first attempts to describe the dielectric properties of water on the microscopic
level were undertaken by Röntgen [7] and Kohlrausch [8]. However, only the ideas
of Bernal and Fowler [9] were elaborated enough to form a basis for the majority
of the modern structural models of both ice and water. Below, we discuss the main
arguments that have been used to develop this famous model of water structure.
3
(a)
(b)
Fig. 1.1 Pictures of two quasi-equilibrium configurations of N = 870 water molecules obtained by
minimizing the combination of Lennard-Jones and Coulomb interactions of pairs of TIP4P/2005model water molecules. a The structure of water. The thermal energy is higher than that allowed for
long-range order formation. b The structure of ice. The thermal energy is low enough for long-range
ordering. The local molecular environment stays nearly the same in both cases. Adapted from [2]
with permission from the PCCP Owner Societies
relatively large data acquisition time and cannot provide a true I-structure test. The
challenge of recent decades is to theorize an I-structure of water, the dynamics of
which would consistently give the V-, D-, and F-structures.
Some studies [4] show that there may be more than one meta-stable structure in
water and ice, which coexist in dynamic equilibrium. This concept has been found
useful for the explanation of neutron diffraction experiments [5], and gives a reason
to talk about the concept of low-density and high-density liquid states. Nevertheless,
a microscopic description of these two states is still lacking. It has recently been
shown that the combination of low-temperature ordered states of water based on
the tetrahedral structure and a high-temperature disordered state based on a distorted
tetrahedron structure can qualitatively explain some anomalies of water [6]. However,
the application of this approach for the explanation of the electrodynamic properties
of water is limited, mainly due to the lack of understanding on how and why these
two different water structures are formed, and change into each other.
1.2 Bragg Scattering and Bernal–Fowler Water
The first attempts to describe the dielectric properties of water on the microscopic
level were undertaken by Röntgen [7] and Kohlrausch [8]. However, only the ideas
of Bernal and Fowler [9] were elaborated enough to form a basis for the majority
of the modern structural models of both ice and water. Below, we discuss the main
arguments that have been used to develop this famous model of water structure.