144
4 The Dielectric Properties and Dynamic Structure of Water and Ice
V-structure, and the D-structure (see Sect. 1.1 for definitions) all together. The ionic
model describes a wider range of experimental data. In particular it (a) eliminates
the contradictions between the tracer diffusion (see Sect. 1.4), the mechanism of
proton conduction and the nuclear magnetic resonance data; (b) uniformly describes
the dielectric relaxation (microwave spectrum), the secondary relaxation (terahertz
spectrum), and DC conductivity; (c) unambiguously determines the lifetimes of water
molecules and ions; (d) qualitatively explains the thermodynamic and structural
anomalies of water without the concept of hydrogen bonding; (e) provides a new
insight to the modeling of the electrodynamic properties of water and ice at ultrashort
(picosecond) timescales.
Thus, the molecular dynamics in water are complex, involving individual intermolecular proton migrations, and the collective behavior of short-lived ionic and
molecular species. The excess protons, which are absent in the Bernal–Fowler model
(see Fig. 1.7), create a spatial and temporal heterogeneity of water. The presence of
short-lived ionic species was recently detected by means of infrared spectroscopy
(see [10]). One can imagine the excess proton-proton-hole “gas”, which exists in
the frame of reference of the neutral water molecules, and moves in the potential
landscape obeying Brownian motion in the electrostatic field of each other in the
polarizable environment (see Fig. 4.5). The dynamics of the proton-hole gas quantitatively describes the broadband dielectric response of water and ice from DC current
to terahertz (see Sect. 3.5).
4.3 Comparison of the Ionic Model with Other Microscopic
Models of Water
Many different models of water have been suggested over the past hundred years [13,
28–35]. Most of them operate as a molecular system and are based on the ideas of
Bernal and Fowler [13] discussed in Chap. 1. The ionic model of water described
above is the natural extension of the Bernal–Fowler model but is not in line with
the previous models. The ionic model does not postulate the molecular species as
the basic structural element and it accounts for the previously missed nuclear quantum effects and processes at ultrashort (picosecond) time intervals, such as proton
exchange and the formation of short-lived ionic species of high instantaneous concentration. To understand the range of the validity of this model, let us compare the
ionic model with standard Bernal–Fowler water.
Standard Bernal–Forler water can be described as follows [36]. The structure of
water (see Fig. 1.5) is viewed as having a uniform three-dimensional network formed
by hydrogen-bonded molecules. The arrangement of this network is dynamically
and structurally inhomogeneous. The water molecules continuously change their
neighbors, so that the average lifetime of bonds is about a few picoseconds.
The ionic model describes water in a different way. Water is represented by an
ensemble of neutral molecules and spontaneously formed short-lived intrinsic ionic
4 The Dielectric Properties and Dynamic Structure of Water and Ice
V-structure, and the D-structure (see Sect. 1.1 for definitions) all together. The ionic
model describes a wider range of experimental data. In particular it (a) eliminates
the contradictions between the tracer diffusion (see Sect. 1.4), the mechanism of
proton conduction and the nuclear magnetic resonance data; (b) uniformly describes
the dielectric relaxation (microwave spectrum), the secondary relaxation (terahertz
spectrum), and DC conductivity; (c) unambiguously determines the lifetimes of water
molecules and ions; (d) qualitatively explains the thermodynamic and structural
anomalies of water without the concept of hydrogen bonding; (e) provides a new
insight to the modeling of the electrodynamic properties of water and ice at ultrashort
(picosecond) timescales.
Thus, the molecular dynamics in water are complex, involving individual intermolecular proton migrations, and the collective behavior of short-lived ionic and
molecular species. The excess protons, which are absent in the Bernal–Fowler model
(see Fig. 1.7), create a spatial and temporal heterogeneity of water. The presence of
short-lived ionic species was recently detected by means of infrared spectroscopy
(see [10]). One can imagine the excess proton-proton-hole “gas”, which exists in
the frame of reference of the neutral water molecules, and moves in the potential
landscape obeying Brownian motion in the electrostatic field of each other in the
polarizable environment (see Fig. 4.5). The dynamics of the proton-hole gas quantitatively describes the broadband dielectric response of water and ice from DC current
to terahertz (see Sect. 3.5).
4.3 Comparison of the Ionic Model with Other Microscopic
Models of Water
Many different models of water have been suggested over the past hundred years [13,
28–35]. Most of them operate as a molecular system and are based on the ideas of
Bernal and Fowler [13] discussed in Chap. 1. The ionic model of water described
above is the natural extension of the Bernal–Fowler model but is not in line with
the previous models. The ionic model does not postulate the molecular species as
the basic structural element and it accounts for the previously missed nuclear quantum effects and processes at ultrashort (picosecond) time intervals, such as proton
exchange and the formation of short-lived ionic species of high instantaneous concentration. To understand the range of the validity of this model, let us compare the
ionic model with standard Bernal–Fowler water.
Standard Bernal–Forler water can be described as follows [36]. The structure of
water (see Fig. 1.5) is viewed as having a uniform three-dimensional network formed
by hydrogen-bonded molecules. The arrangement of this network is dynamically
and structurally inhomogeneous. The water molecules continuously change their
neighbors, so that the average lifetime of bonds is about a few picoseconds.
The ionic model describes water in a different way. Water is represented by an
ensemble of neutral molecules and spontaneously formed short-lived intrinsic ionic