The striking similarity of ac conduction in quite different disordered solids is discussed terms experimental results, modeling, and computer simulations. After giving an overview experiment, a macroscopic microscopic model are reviewed. For both models the normalized conductivity as function suitably scaled frequency becomes independent details disorder extreme limit, i.e., when local randomly varying mobilities cover many orders magnitude. two universal conductivities similar, but not...

Basic characteristics of the liquid-glass transition are reviewed, emphasizing its universality and briefly summarizing most popular phenomenological models. Discussion is focused on a number alternative models which one way or other connect fast slow degrees freedom viscous liquids. It shown that all these ``elastic'' equivalent in simplest approximation.

A brief review of the history ac ionic and electronic conduction in disordered solids is given, followed by a detailed discussion simplest possible realistic model: random free-energy barrier model. This model assumes takes place hopping, where hopping charge carriers are subject to spatially randomly varying energy barriers. The solved continuous time walk effective medium approximation, it shown that two solutions almost indistinguishable. In model, frequency-dependent conductivity...

This paper is the fourth in a series devoted to identifying and explaining properties of strongly correlating liquids, i.e., liquids where virial potential energy correlate better than 90% their thermal equilibrium fluctuations NVT ensemble. For such we here introduce concept "isomorphic" curves phase diagram. A number thermodynamic, static, dynamic isomorph invariants are identified. These include excess entropy, isochoric specific heat, reduced-unit static correlation functions, as well...

A number of basic scientific questions relating to ion conduction in homogeneously disordered solids are discussed. The deal with how define the mobile density, what can be learnt from electrode effects, transport mechanism is, role dimensionality and origins mixed-alkali effect, time-temperature superposition, nearly constant loss are. Answers suggested some these questions, but main purpose paper is draw attention fact that this field research still presents several fundamental challenges.

This article gives an overview of excess-entropy scaling, the 1977 discovery by Rosenfeld that entropy determines properties liquids like viscosity, diffusion constant, and heat conductivity. We give examples from computer simulations confirming this intriguing connection between dynamics thermodynamics, counterexamples, experimental validations. Recent uses in application-related contexts are reviewed, theories proposed for origin scaling briefly summarized. It is shown if two thermodynamic...

Recent developments show that many liquids and solids have an approximate "hidden" scale invariance implies the existence of lines in thermodynamic phase diagram, so-called isomorphs, along which structure dynamics properly reduced units are invariant to a good approximation. This means diagram becomes effectively one-dimensional with regard several physical properties. Liquids isomorphs include most or all van der Waals bonded systems metals, as well weakly ionic dipolar systems. On other...

A model for the viscosity of glass-forming molecular liquids is proposed in which a ``flow event'' requires local volume increase. The activation energy flow event identified with work done shoving aside surrounding liquid; this proportional to high-frequency shear modulus, increases as temperature decreases. confirmed by experiments on number liquids. \textcopyright{} 1996 American Physical Society.

An equilibrated model glass-forming liquid is studied by mapping successive configurations produced molecular dynamics simulation onto a time series of inherent structures (local minima in the potential energy). Using this ``inherent dynamics'' approach we find direct numerical evidence for long held view that below crossover temperature, $T_x$, liquid's can be separated into (i) vibrations around and (ii) transitions between (M. Goldstein, J. Chem. Phys. {\bf 51}, 3728 (1969)), i.e., become...

Recent scaling results for the ac conductivity of ionic glasses by Roling et al. [Phys. Rev. Lett. 78, 2160 (1997)] and Sidebottom 82, 3653 (1999)] are discussed. We prove that Sidebottom's version is completely general. A new approximation to universal arising in extreme disorder limit symmetric hopping model, "diffusion cluster approximation," presented compared computer simulations experiments.

Simulations involving the Lennard-Jones potential usually employ a cutoff at r = 2.5σ. This communication investigates possibility of reducing cutoff. Two different implementations are compared, standard shifted and less commonly used forces The first has correct below cutoff, whereas modifies Newton's equations all distances. latter is nevertheless superior; we find that for most purposes realistic simulations may be obtained using 1.5σ, even though pair force here 30 times larger than

Strong correlations between equilibrium fluctuations of the configurational parts pressure and energy are found in computer simulations Lennard-Jones liquid other simple liquids, but not for hydrogen-bonding liquids such as methanol water. The that present also crystal glass phases reflect an effective inverse power-law repulsive potential dominating fluctuations, even at zero slightly negative pressure. In experimental data supercritical argon, to be approximately 96%. Consequences viscous...

We show that a number of model liquids at fixed volume exhibit strong correlations between equilibrium fluctuations the configurational parts (instantaneous) pressure and energy. present detailed results for 13 systems, showing in which systems these are significant. These include Lennard-Jones (both single- two-component) several other simple liquids, neither hydrogen-bonding such as methanol water, nor Dzugutov liquid, has significant contributions to second nearest neighbor distance. The...

This topical review discusses the quasiuniversality of simple liquids' structure and dynamics two possible justifications it. The traditional one is based on van der Waals picture liquids in which hard-sphere system reflects basic physics. An alternative explanation argues that all quasiuniversal to a good approximation conform same equation motion, referring exponentially repulsive pair-potential as reference system. paper, aimed at non-experts, ends by listing number open problems field.

We present a detailed analysis and discuss consequences of the strong correlations configurational parts pressure energy in their equilibrium fluctuations at fixed volume reported for simulations several liquids previous paper [N. P. Bailey et al., J. Chem. Phys. 129, 184507 (2008)]. The concentrates specifically on single-component Lennard-Jones system. demonstrate that potential may be replaced, volume, by an effective power law but not simply because only short-distance encounters...

What is a simple liquid? It seems an entirely banal question to those working in statistical physics, chemical and physical chemistry of liquids soft matter. A group Danish physicists show that asking this can actually lead new illuminating understanding liquid physics.

Supercooled liquids are characterized by relaxation times that increase dramatically cooling or compression. From a single assumption follows scaling law according to which the time is function of h(ρ) over temperature, where ρ density and depends on liquid in question. This demonstrated work well for simulations Kob–Andersen binary Lennard-Jones mixture two molecular models, as experimental results van der Waals liquids, dibutyl phthalate decahydroisoquinoline. The often used power-law...

Rosenfeld proposed two different scaling approaches to model the transport properties of fluids, separated by 22 years, one valid in dilute gas, and another liquid phase. In this work, we demonstrate that these limiting cases can be connected through use a novel approach bridging function. This approach, which is empirical not derived from theory, used generate reference correlations for Lennard-Jones 12-6 fluid viscosity, thermal conductivity, self-diffusion. with very simple functional...

Liquids composed of small-molecule monohydroxy alcohols are demonstrated to display rheological behavior typical for oligomeric chains. This observation was made possible by experiments in which more than seven decades frequency and five on the mechanical modulus scale covered. The singly hydrogen-bonded were chosen because they significant, but surprisingly poorly understood effects intermolecular association. Based present shear study, one can apply theoretical concepts polymer science...