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Elucidating the underlying mechanisms of water solidification in heterogeneous systems is crucially important for a panoply of applications; gaining such an understanding has also proven to be very challenging to the community. Indeed, one such example lies in clarifying the thermodynamics and kinetics of electro-crystallization in heterogeneous systems, such as micro- and nano-bubble systems. Here, we employ non-equilibrium molecular dynamics of water in heterogeneous environments experiencing direct contact with a propane gas phase at various temperatures in externally applied static electric fields, elucidating significant external-field effects in inducing poly-crystalline cubic-ice formation. This is in stark contrast with recent work on homogeneous cubic-ice electro-nucleation to produce largely fault-free single crystals. We explore the kinetics of heterogeneous cubic-ice electro-nucleation under different field intensities and thermal conditions and provide an overview of time-dependent dynamics of evolution of polycrystallinity. [ABSTRACT FROM AUTHOR]

Human aquaporin 4 has been studied using non-equilibrium molecular dynamics simulations in the absence and presence of pulses of external electric fields. The pulses were 100 ns in duration and 0.005–0.015 V/Å in intensity acting along the pores' axes. Water diffusivity and the dipolar response of various residues of interest within the pores have been studied. Results show relatively little change in levels of water permeability per se within aquaporin channels during axially oriented field impulses, although care must be taken with regard to statistical certainty. However, the spatial variation of water permeability vis-à-vis electric-field intensity within the milieu of the channels, as revealed by heterogeneity in diffusivity-map gradients, indicates the possibility of somewhat enhanced diffusivity, owing to several residues being affected substantially by external fields, particularly for HIS 201 and 95 and ILE 93. This has the effect of increasing slightly intra-pore water diffusivity in the "pore-mouths" locale, albeit rendering it more spatially uniform overall vis-à-vis zero-field conditions (via manipulation of the selectivity filter). [ABSTRACT FROM AUTHOR]

The response of water to externally applied electric fields is of central relevance in the modern world, where many extraneous electric fields are ubiquitous. Historically, the application of external fields in non-equilibrium molecular dynamics has been restricted, by and large, to relatively inexpensive, more or less sophisticated, empirical models. Here, we report long-time non-equilibrium ab initio molecular dynamics in both static and oscillating (time-dependent) external electric fields, therefore opening up a new vista in rigorous studies of electric-field effects on dynamical systems with the full arsenal of electronic-structure methods. In so doing, we apply this to liquid water with state-of-the-art non-local treatment of dispersion, and we compute a range of field effects on structural and dynamical properties, such as diffusivities and hydrogen-bond kinetics. [ABSTRACT FROM AUTHOR]

We have performed non-equilibrium molecular dynamics simulations of various TiO2/water interfaces at ambient temperature in presence of oscillating electric fields in frequency range 20-100 GHz and RMS intensities 0.05-0.25 V/Å. Although the externally applied fields are by one order of magnitude lower than the intrinsic electric field present on the interfaces (1.5-4.5 V/Å), significant non-thermal coupling of rotational and translational motion of water moleculeswas clearly observed. Enhancement of the motion, manifested by increase of diffusivity, was detected in the first hydration layer, which is known to be heavily confined by adsorption to the TiO2 surface. Interestingly, the diffusivity increases more rapidly on anatase than on rutile facets where the adsorbed water was found to be more organized and restrained. We observed that the applied oscillating field reduces number of hydrogen bonds on the interface. The remaining H-bonds are weaker than those detected under zerofield conditions; however, their lifetime increases on most of the surfaces when the low-frequency fields are applied. Reduction of adsorption interaction was observed also in IR spectra of interfacial water where the directional patterns are smeared as the intensities of applied fields increase. [ABSTRACT FROM AUTHOR]

Water has many intriguing and anomalous physical properties that have puzzled and titillated the scientific community for centuries, perhaps none more so than the proposition that water may retain some (permanent) "memory" of conditions (e.g., dilution) or electric fields to which it has been subject. Here, we have performed non-equilibrium molecular dynamics simulations of liquid water in external electric-field nanosecond pulses, at 260-310 K, and gauged significant non-thermal field effects in terms of dipolar response. Response of both system- and individual-dipoles has been investigated, and autocorrelation functions of both show more significant effects in stronger fields, with more sluggish relaxation. Crucially, we show that once the field is removed, the dipoles relax, exhibiting no memory or permanent dipolar alignment. We also quantify the time scales for system dynamical-dipolar properties to revert to zero-field equilibrium behaviour. [ABSTRACT FROM AUTHOR]

The one-dimensional Schrödinger equation, applied to the H2 intramolecular stretch coordinate in singly to quadruply occupied large cages in extended Type II (sII) hydrogen clathrate hydrate, was solved numerically herein via potential-energy scans from classical molecular dynamics (MD), employing bespoke force-matched H2–water potential. For both occupation cases, the resultant H–H stretch spectra were redshifted by ~350 cm−1 vis-à-vis their classically sampled counterparts, yielding semi-quantitative agreement with experimental Raman spectra. In addition, ab initio MD was carried out systematically for different cage occupations in the extended sII hydrate to assess the effect of differing intra-cage intrinsic electric field milieux on H–H stretch frequencies; we suggest that spatial heterogeneity of the electrostatic environment is responsible for some degree of peak splitting. [ABSTRACT FROM AUTHOR]

Water self-diffusion and the dipolar response of the selectivity filter within human aquaporin 4 have been studied using molecular dynamics (MD) simulations in the absence and presence of pulses of external static and alternating electric fields. The pulses were approximately 50 and 100 ns in duration and 0.0065 V/Å in (r.m.s.) intensity and were either static or else 2.45 or 100 GHz in frequency and applied both along and perpendicular to the channels. In addition, the relaxation of the aquaporin, water self-diffusion and gating dynamics following cessation of the impulses was studied. In previous work it was determined that switches in the dihedral angle of the selectivity filter led to boosting of water permeation events within the channels, in the presence of identical external static and alternating electric fields, although applied continuously. Here the application of field impulses (and subsequently, upon removal) has shown that it is the dipolar orientation of the histidine-201 residue in the selectivity filter which governs the dihedral angle, and hence influences water self-diffusion; this constitutes an appropriate order parameter. The dipolar response of this residue to the applied field leads to the adoption of four distinct states, which we modelled as time-homogeneous Markov jump processes, and may be distinguished in the potential of mean force (PMF) as a function of the dipolar orientation of histidine-201. The observations of enhanced 'dipolar flipping' of H201 serve to explain increased levels of water self-diffusion within aquaporin channels during, and immediately following, field impulses, although the level of statistical certainty here is lower. Given the appreciable size of the energy barriers evident in PMFs computed directly from deterministic MD (whether in the absence or presence of external fields), metadynamics calculations were undertaken to explore the free-energy landscape of histidine-201 orientation with greater accuracy and precision. These indicate that electric fields do alter the free-energy profile of the H201 side-chain orientation, wherein a perturbation of the symmetric bimodal state evident in the zero-field case is observed. These effects are dependent on the field intensities. [ABSTRACT FROM AUTHOR]

Water self-diffusion within human aquaporin 4 has been studied using molecular dynamics (MD) simulations in the absence and presence of external ac and dc electric fields. The computed diffusive (pd) and osmotic (pf) permeabilities under zero-field conditions are (0.718 ± 0.24) × 10-14 cm3 s-1 and (2.94 ± 0.47) × 10-14 cm3 s-1, respectively; our pf agrees with the experimental value of (1.50 ± 0.6) × 10-14 cm3 s-1. A gating mechanism has been proposed in which side-chain dynamics of residue H201, located in the selectivity filter, play an essential role. In addition, for nonequilibrium MD in external fields, it was found that water dipole orientation within the constriction region of the channel is affected by electric fields (e-fields) and that this governs the permeability. It was also found that the rate of side-chain flipping motion of residue H201 is increased in the presence of e-fields, which influences water conductivity further. [ABSTRACT FROM AUTHOR]

Water-self-diffusion through single-walled carbon nanotubes (SWCNTs) inserted normal to a phospholipid membrane has been studied using equilibrium and nonequilibrium molecular dynamics simulations in the presence of static and alternating electrical fields. Four different SWCNTs were investigated: (5,5), (6,6), (8,8), and (11,11) and also three arrays of four (6,6) SWCNTs separated by 15, 20, and 25 Å, respectively. The (5,5) system shows interesting behavior, where an increase in the applied field frequency in the z direction decreases the water permeation rates, reaching values at higher frequencies similar to zero-field conditions. The (6,6) arrays simulations demonstrated that there is a friction effect, when the nanotubes are closely packed, which retards the movement of the individual water files. [ABSTRACT FROM AUTHOR]

Nonequilibrium molecular-dynamics (MD) simulations have been performed for the growth and dissolution of a spherical methane hydrate crystallite, surrounded by a saturated water–methane liquid phase, in both the absence and presence of external electromagnetic (e/m) fields in the microwave to far infrared range (5–7500 GHz) at root-mean square (rms) electric field intensities of up to 0.2 V/Å. A rigid/polarizable potential was used to model water and a rigid/nonpolarizable model was utilized for methane. In the absence of a field, it was found that the average growth rate of the crystallite was ∼0.32 water and 0.045 methane molecules per picosecond, evaluated over a 500 ps NPT simulation for three different initial geometries. Upon the application of an e/m field, it was found that no significant deviations from the zero-field crystal growth patterns were observed for rms electric field intensities of less than about 0.1 V/Å, regardless of the field frequency. At, and above, this “threshold” intensity, it was found that dissolution took place. The mobility of the molecules in the system was enhanced by the e/m field, to the greatest extent for frequencies of 50–100 GHz. Furthermore, it was observed that there was a systematic frequency variation in the pattern of dipole alignment with the external field and this led to marked differences in the rate of dissolution. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

• Heating increases H-bond lengths and A–D–H angles, while number of H-bonds reduced with increasing field strength. • As temperature increases, increased rate of H-bond breakage influenced rapid decay of H-bonds' lifetimes for zero- and static-field conditions. • Heating induces shorter correlation times for zero-field conditions while oscillating fields revealed more rapid autocorrelation decay. Water, as simultaneously the most intriguing and ubiquitous liquid on the planet, holds central relevance in our world – and displays a suite of fascinating anomalies. Of notable interest in this study is the leveraging of non-equilibrium molecular dynamics (NEMD) simulation to study the response of water molecules under the influence of external electric-fields while subjected to temperature changes. In particular, external static and oscillating electric fields with varying (r.m.s) intensities 0.05 V / Å and 0.10 V / Å and oscillating-field frequencies 50 , 100 and 200 G H z were examined to gauge the influence of supercooled and nearer-ambient temperature regions on water structure and interaction, dynamical properties, dipolar response, hydrogen-bond kinetics and lifetime. Interestingly, the impact of heating the system was accentuated with increase in the hydrogen-bond lengths, and A–D–H angles while the number of hydrogen-bonds reduced with increase in the temperature for all the fields conditions, although slight variations were observed under the influence of static and oscillating fields. Furthermore, as temperature increases, the increased rate of hydrogen-bond breakage influenced the rapid decay of hydrogen-bond lifetimes for zero- and static-field conditions, while molecular rotations caused by dipole-alignment response to the oscillating fields enhanced to a greater extent the mobility of the molecules, and also increased the rate of hydrogen-bond breakage and diffusivity due to the increased thermal motion. Moreover, the effect of increasing the temperature on the polarisation properties of the liquid weakened the hydrogen-bond network and also led to a decrease in the molecular and time response of the system's dipole moment; higher temperature and field intensity invoked more rapid system dipolar alignment, in addition to the frequency relating to longer periods and greater intensity. With increasing temperature, the behaviour of system dynamics revealed shorter correlation times for zero-field conditions while oscillating-field with increased intensity revealed more rapid autocorrelation decay in comparison to those with reduced intensity. Indeed, the presence of much longer correlation time manifested by zero-field conditions in the supercooled temperature region evinced succinctly the lack of rotational motion that allows for more rapid decay time. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Water clusters (2, 6, 12 and 20) are simulated under additional forces of varying magnitude of 0.1–25 % of the total force. • The original cluster breaks immediately within 1 ns and alternate arrangements are taken up even at low fields. • The librational peaks are most effected with 20 water clusters being most effected, they are suppressed with time. Abstract Water clusters are hydrogen bonded molecular assembly of water molecules. They have been extensively studied using experiments, ab initio calculations and molecular simulations. The molecular arrangement of water in water cluster provide significant insights into behavior of water in bulk, confinement and close to surfaces. Here molecular dynamics simulations of TIP4P/2005 water clusters are performed in weak electrid fields. These fields introduce additional forces of varying magnitude 0.1–25 % of forces existing in without-field water clusters. Autocorrelation functions of distance, energy and velocities are analysed. Molecular arrangements in water clusters does not disintegrate under additional forces. [ABSTRACT FROM AUTHOR]

Non-equilibrium molecular-dynamics (NEMD) simulations of bulk methane clathrate hydrates have been conducted in a range of externally-applied static electric fields of up to 2.0 V·nm −1 in intensity, at 250 K and 60 atm. Studies into frequencies of system-mass-density fluctuations showed that these clathrates have two major modes: the dominant one is attributable to water molecules’ librations and occurs at 720 cm −1 , regardless of applied fields. A more minor global density fluctuation arises at 10–12 cm −1 , due to the propagation of local-density fluctuations; again, this is independent of applied fields. A threshold intensity of 1.2 V·nm −1 was necessary to overcome the strong clathrate hydrogen-bonding network to produce any appreciable structural changes. Aside from variations in hydrate system density per se , a key interest in this study was (electro-) dissociation; a number of analysis methods were used to gauge this, including system-density and configurational-energy studies (and their respective autocorrelation functions and corresponding Fourier transforms), as well as radial distribution functions (RDFs) and density of states (DOS). In terms of electro-dissociation itself, a ‘plateau’ intensity of 1.6 V·nm −1 led to outright dissociation over the 0.5 ns timescales probed in the current study, where any field intensity above this level produced essentially identical dissociation outcomes: a marked loss of hydrate structure and increase in system configurational energy. RDF analysis of electro-dissociation indicates the collapse of the host lattice towards an amorphous structure and concomitant release of methane molecules from their now-collapsed cages to form a ‘nano-bubble’. Upon post-dissociation field removal, it was found that this process was irreversible: the system transitions to an entirely new, less dense structure, featuring a phase-segregated methane nano-bubble within a liquid-like aqueous phase. [ABSTRACT FROM AUTHOR]

Human aquaporin 4 has been studied using molecular dynamics (MD) simulations in the absence and presence of pulses of external static electric fields. The pulses were 10 ns in duration and 0.012-0.065 V/Å in intensity acting along both directions perpendicular to the pores. Water permeability and the dipolar response of all residues of interest (including the selectivity filter) within the pores have been studied. Results showed decreased levels of water osmotic permeability within aquaporin channels during orthogonally-oriented field impulses, although care must be taken with regard to statistical certainty. This can be explained observing enhanced "dipolar flipping" of certain key residues, especially serine 211, histidine 201, arginine 216, histidine 95 and cysteine 178. These residues are placed at the extracellular end of the pore (serine 211, histidine 201, and arginine 216) and at the cytoplasm end (histidine 95 and cysteine 178), with the key role in gating mechanism, hence influencing water permeability. [ABSTRACT FROM AUTHOR]

Non-equilibrium molecular dynamics simulations of liquid water have been performed at 298 K in the presence of external time-varying electric fields, approximating a square wave, of varying peak intensity (0.005–0.1 V/Å) in the microwave to far-infrared frequency range (20–500 GHz). Significant non-thermal field effects were noted in terms of dipolar response and acceleration of hydrogen-bond kinetics. The coupling between the total dipole moment and the external field has been investigated and autocorrelation functions (ACFs) of both the total dipole moment and the average of the individual molecular dipole moment along the laboratory axis of the applied fields exhibited coupling, with the former showing a stronger coupling and the latter showing coupling to lower magnitude fields. The maximum alignment achieved has been computed as a function of field intensities and frequencies: the lower frequencies show a greater maximum alignment as the system had more time within each field cycle to respond. The normalised probability distribution and the hydrogen-bond ACFs have been computed: the ACF showed a clear effect over shortening the hydrogen-bond relaxation time. The field effects over the molecules’ transitions from four to five hydrogen bonds have been computed. There was an enhancement of fewer molecules undergoing transitions and a dampening for a larger proportion of molecules, depending on the external fields’ periods. [ABSTRACT FROM PUBLISHER]

Highlights: [•] Significant field effects noted in coupling of rotational and translational motion. [•] Non-linear field effects were evident above around 0.05VÅ−1 intensity. [•] Translational and librational modes orthogonal to field promoted. [•] Coupling of periods with dipolar and hydrogen bonding relaxation timescales important. [ABSTRACT FROM AUTHOR]

The non-thermal effects of external electric and electromagnetic fields in the microwave to far-infrared frequency range and at (r.m.s.) electric field intensities of 10-3 to 0.25 V/År.m.s. on neat salts of 1,3-dimethyl-imidazolium hexafluorophosphate ([dmim][PF6]) and 1-butyl-3-methyl-imidazolium hexafluorophosphate ([bmim][PF6]) have been investigated by means of non-equilibrium molecular dynamics simulation. Significant alterations in molecular mobility were found vis-a-vis zero-field conditions. Using Green-Kubo and transient time correlation function analysis, the electrical conductivity of these ionic liquids has been estimated. The results indicate that ionic liquids respond most significantly to frequencies much lower than those of smaller polar solvents such as water, although the mechanism of the field response is almost exclusively translational. [ABSTRACT FROM AUTHOR]

Abstract: The non-thermal response of neat dimethylimidazolium chloride salts and their binary mixtures with water have been investigated by means of non-equilibrium molecular dynamics simulation at an electric field intensity of 10−3 V/Å, in terms of electrical conductivity and dipolar relaxation (as metrics of translational and rotational response, respectively). Using Green-Kubo and transient time correlation function (TTCF) analysis, the electrical conductivity of each system has been estimated. It was found that the systems'' conductivity at 450K increased, while dipolar relaxation times for both water molecules and dimethylimidazolium ions decreased, with decreasing ionic liquid mole fraction. This indicates greater scope for accelerated response to external electric fields in less associated ionic liquids. [Copyright &y& Elsevier]

Abstract: Non-equilibrium molecular dynamics (NEMD) simulations have been performed for static electric fields for a range of positively charged spherical rutile–titania nanoparticles with radii of 1.5 to 2.9 nm for two different salt concentrations in water, in order to simulate electrophoresis directly. Using the observed limiting drag velocities, Helmholtz–Smoluchowski (HS) theory was used to estimate their potentials. These estimates were compared to values from numerical solution of the non-linear Poisson–Boltzmann (PB) equation for representative configurations of the nanoparticles, in addition to idealised analytic and Debye–Hückel (DH) solutions about spherical particles of the same geometry and charge state, for the given salt concentrations. It was found that reasonable agreement was obtained between the various approaches, with the NEMD-HS results some 15%–15% smaller than the numerical PB results for more highly charged nanoparticles. [Copyright &y& Elsevier]

The grand challenges in renewable energy lie in our ability to comprehend efficient energy conversion systems, together with dealing with the problem of intermittency via scalable energy storage systems. Relatively little progress has been made on this at grid scale and two overriding challenges still need to be addressed: (i) limiting damage to the environment and (ii) the question of environmentally friendly energy conversion. The present review focuses on a novel route for producing hydrogen, the ultimate clean fuel, from the Sun, and renewable energy source. Hydrogen can be produced by light-driven photoelectrochemical (PEC) water splitting, but it is very inefficient; rather, we focus here on how electric fields can be applied to metal oxide/water systems in tailoring the interplay with their intrinsic electric fields, and in how this can alter and boost PEC activity, drawing both on experiment and non-equilibrium molecular simulation. [ABSTRACT FROM AUTHOR]

• Externally-applied electric fields are shown to boost photo-electrochemical water splitting under certain conditions. • Study of both static and oscillating electric fields. • Experimental and molecular-simulation evidence. • Quantification of AC- and DC-field effects on number of water-lysis events. Given that conversion efficiencies of incident solar radiation to liquid fuels, e.g. , H 2 , are of the order of a few percent or less, as quantified by 'solar to hydrogen' (STH), economically inexpensive and operationally straightforward ways to boost photo-electrochemcial (PEC) H 2 production from solar-driven water splitting are important. In this work, externally-applied static electric fields have led to enhanced H 2 production in an energy-efficient manner, with up to ~30–40% increase in H 2 (bearing in mind field-input energy) in a prototype, open-type solar cell featuring rutile/titania and hematite/iron-oxide (Fe2O 3), respectively, in contact with an alkaline aqueous medium (corresponding to respective relative increases of STH by ~12 and 16%). We have also performed non-equilibrium ab-initio molecular dynamics in both static electric and electromagnetic (e/m) fields, for water in contact with a hematite/iron-oxide (0 0 1) surface, observing enhanced break-up of water molecules, by up to ~70% in the linear-response régime. We discuss the microscopic origin of such enhanced water-splitting, based on experimental and simulation-based insights. In particular, we external-field direction at the hematite surfaces, and scrutinise properties of the adsorbed water molecules and OH– and H 3 O+ species, e.g. , hydrogen bonds between water-protons and the hematite surfaces' bridging oxygen atoms, as well as interactions between oxygen atoms in adsorbed water molecules and underlying iron atoms. [ABSTRACT FROM AUTHOR]

Unpacking the mechanistic insights into how externally applied electric fields affect the physicochemical properties of crystals represents a challenge of great importance for a plethora of natural phenomena, in addition to a broad array of industrial operations and technologies. As such, the key goals in such field effect studies centre around how thermodynamic and kinetic relaxation processes in crystals are affected, including charge carrier conduction and energy transfer processes, and this is a very recent area of fundamental scrutiny. Indeed, in recent years, there has been a steadily mounting number of reports of field-manipulated crystal-state phenomena. Taking as the background a range of natural phenomena, phenomenological theory, state-of-the-art experiments and technological observations, the present review examines the role of nonequilibrium molecular simulation in its scrutiny of intra-crystal phenomena from an atomistic viewpoint, in addition to providing a framework for a predictive molecular design philosophy by which to refine field crystal understanding. [ABSTRACT FROM AUTHOR]

Non-equilibrium molecular dynamics (MD) of small, charged cadmium selenide nanorods have been carried out in the absence and presence of static applied electric fields. In the absence of applied fields, it was found that opposite dipolar alignment (antiferromagnetic) was achieved, along with self-assembly of the nanorods. However, in the case of induced electrophoresis in applied fields, the rods approached each other less readily, while at and above a field intensity of 0.05 V/Å, preferential alignment with the field was achieved for all rods, in contrast to the zero-field case. These results have implications for electric field-mediated control of nanorod assembly in solution, of key importance in a wide range of areas from photovoltaics to energy storage. [ABSTRACT FROM AUTHOR]

Elucidating the underlying mechanisms of molecular solidification in both homo- and hetero-geneous systems is of paramount importance for a large swathe of natural phenomena (whether on Earth or throughout the Universe), as well as a whole litany of industrial processes. One lesser-studied aspect of these disorder-order transitions is the effect of external applied fields, shifting both thermodynamic driving forces and underlying kinetics, and, indeed, fundamental mechanisms themselves. Perhaps this is nowhere more apparent than in the case of externally-applied electric fields, where there has been a gradually increasing number of reports in recent years of electro-manipulated crystallisation imparted by such electric fields. Drawing motivations from both natural phenomena, state-of-the-art experiments and, indeed, industrial applications, this review focusses on how non-equilibrium molecular simulation has helped to elucidate crystallisation phenomena from a microscopic perspective, as well as offering an important, predictive molecular-design approach with which to further refine in-field-crystallisation operations. [ABSTRACT FROM AUTHOR]

[Display omitted] • External electric fields shift dipole moment distribution of hematite-adsorbed water. • Significant doubling in the adsorbed-water self-diffusion constants, including at individual molecular level. • Marked field-induced shift in infrared-vibrational properties. • Underlying "dipole-locking" mechanism at play for water-dipole alignment with applied field. The dynamical properties of physically and chemically adsorbed water molecules at a pristine hematite-(0 0 1) surfaces have been studied by non-equilibrium ab-initio molecular dynamics in the constant-volume, constant-temperature ensemble at room temperature, under externally-applied, uniform static electric fields of increasing intensity. Significant alterations in the dipole moment and self-diffusion constant were found vis-à-vis zero-field conditions, as well as shifting of the probability distribution of individual molecular self-diffusivities. For instance, application of static fields was found to increase the self-diffusion of water molecules at the α-hematite Fe 2 O 3 surface, effectively due to some extent of 'dipole-locking' in the direction of the applied field. [ABSTRACT FROM AUTHOR]

The article presents a study related to the possibility of realizing superionic ice VII in external electric fields of planetary bodies. It mentions about the superionic (SI) ice behavior in ice VII by means of externally applied electric fields, using state-of-the-art nonequilibrium ab initio molecular dynamics to witness at first hand the protons' fluid dance through a dipole-ordered ice VII lattice.

Non-equilibrium molecular-dynamics simulations of liquid water have been performed in the canonical ensemble in the presence of both external static and oscillating electric fields of (r.m.s.) intensities 0.05 V/Å and 0.10 V/Å, with oscillating-field frequencies 50, 100 and 200 GHz. The rigid potential model TIP4P/2005 was used, and NEMD simulations were performed, including in the supercooled region, at temperatures ranging from 200 to 310 K. Significant alterations in the percentage dipole alignment and self-diffusion constant were found vis-à-vis zero-field conditions, as well as shifting of the probability distribution of individual molecular self-diffusivities. For instance, the application of static fields was typically found to reduce the self-diffusion of liquid water, effectively due to some extent of 'dipole-locking', or suppression of rotational motion, whilst diffusivity was found to be enhanced in oscillating fields, especially at high frequencies and outside the supercooled region. • Statistical study of probability distributions of individual molecules' self-diffusivity • Study of both static and oscillating electric fields • Derivation of temperature dependence of diffusivities in supercooled and nearer-ambient conditions • Detailed assessment of shifts in molecular-diffusivity distributions by externa fields of varying type [ABSTRACT FROM AUTHOR]