In materials science the phase-field crystal approach has become popular to model crystallization processes. Phase-field crystal models are in essence Landau-Ginzburg-type models, which should be derivable from the underlying microscopic description of the system in question. We present a study on classical density functional theory in three stages of approximation leading to a specific phase-field crystal model, and we discuss the limits of applicability of the models that result from these approximations. As a test system we have chosen the three-dimensional suspension of monodisperse hard spheres. The levels of density functional theory that we discuss are fundamental measure theory, a second-order Taylor expansion thereof, and a minimal phase-field crystal model. We have computed coexistence densities, vacancy concentrations in the crystalline phase, interfacial tensions, and interfacial order parameter profiles, and we compare these quantities to simulation results. We also suggest a procedure to fit the free parameters of the phase-field crystal model. Thereby it turns out that the order parameter of the phase-field crystal model is more consistent with a smeared density field (shifted and rescaled) than with the shifted and rescaled density itself. In brief, we conclude that fundamental measure theory is very accurate and can serve as a benchmark for the other theories. Taylor expansion strongly affects free energies, surface tensions, and vacancy concentrations. Furthermore it is phenomenologically misleading to interpret the phase-field crystal model as stemming directly from Taylor-expanded density functional theory.

The crystallization of a metastable melt is one of the most important non-equilibrium phenomena in condensed matter physics, and hard sphere colloidal model systems have been used for several decades to investigate this process by experimental observation and computer simulation. Nevertheless, there is still an unexplained discrepancy between the simulation data and experimental nucleation rate densities. In this paper we examine the nucleation process in hard spheres using molecular dynamics and Monte Carlo simulation. We show that the crystallization process is mediated by precursors of low orientational bond-order and that our simulation data fairly match the experimental data sets.

We consider the distribution P (φ) of the Hatano-Sasa entropy, φ, in reversible and irreversible processes, finding that the Crook's relation for the ratio of the pdf's of the forward and backward processes, P F (φ)/P R (−φ) = e φ , is satisfied not only for reversible, but also for irreversible processes, in general, in the adiabatic limit of "slow processes." Focusing on systems with a finite set of discrete states (and no absorbing states), we observe that two-state systems always fulfill detailed balance, and obey Crook's relation. We also identify a wide class of systems, with more than two states, that can be "coarse-grained" into two-state systems and obey Crook's relation despite their irreversibility and violation of detailed balance. We verify these results in selected cases numerically.

Entropy production is one of the most important characteristics of non-equilibrium steady states.We study here the steady-state entropy production, both at short times as well as in the long-time limit, of two important classes of non-equilibrium systems: transport systems and reaction-diffusion systems. The usefulness of the mean entropy production rate and of the large deviation function of the entropy production for characterizing non-equilibrium steady states of interacting manybody systems is discussed. We show that the large deviation function displays a kink-like feature at zero entropy production that is similar to that observed for a single particle driven along a periodic potential. This kink is a direct consequence of the detailed fluctuation theorem fulfilled by the probability distribution of the entropy production and is therefore a generic feature of the corresponding large deviation function.

We study the work fluctuations of two types of finite quantum spin chains under the application of a time-dependent magnetic field in the context of the fluctuation relation and Jarzynski equality. The two types of quantum chains correspond to the integrable Ising quantum chain and the nonintegrable XX quantum chain in a longitudinal magnetic field. For several magnetic field protocols, the quantum Crooks and Jarzynski relations are numerically tested and fulfilled. As a more interesting situation, we consider the forcing regime where a periodic magnetic field is applied. In the Ising case we give an exact solution in terms of double-confluent Heun functions. We show that the fluctuations of the work performed by the external periodic drift are maximum at a frequency proportional to the amplitude of the field. In the nonintegrable case, we show that depending on the field frequency a sharp transition is observed between a Poisson-limit work distribution at high frequencies toward a normal work distribution at low frequencies.

We investigate the early part of the crystal nucleation process in the hard sphere fluid using data produced by computer simulation. We find that hexagonal order manifests continuously in the overcompressed liquid, beginning approximately one diffusion time before the appearance of the first "solid-like" particle of the nucleating cluster, and that a collective influx of particles towards the nucleation site occurs simultaneously to the ordering process: the density increases leading to nucleation are generated by the same individual particle displacements as the increases in order. We rule out the presence of qualitative differences in the early nucleation process between medium and low overcompressions and also provide evidence against any separation of translational and orientational order on the relevant lengthscales. C 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license

Motivated by biological aspects related to fungus growth, we consider the competition of growth and corrosion. We study a modification of the totally asymmetric exclusion process, including the probabilities of injection ␣ and death of the last particle ␦. The system presents a phase transition at ␦ c ͑␣͒, where the average position of the last particle ͗L͘ grows as ͱ t. For ␦ Ͼ ␦ c , a nonequilibrium stationary state exists while for ␦ Ͻ ␦ c the asymptotic state presents a low density and max current phases. We discuss the scaling of the density and current profiles for parallel and sequential updates. DOI: 10.1103/PhysRevE.81.042101 PACS number͑s͒: 05.40.Ϫa, 87.10.Hk, 87.10.Rt Fungi are eukaryotic organisms that include microorganisms such as yeasts and molds, as well as the familiar mushrooms. The growth of a fungus is formed by the combination of the apical growth and the branching process which leads to the development of a mycelium. Most of them grow as hyphae, which are a cylindrical thread-like structures of 5 -10 m in diameter and up to several centimeters in length ͓1͔. The apical growth is a quasi-one-dimensional process that extends the hypha by transport of material from the seed to the front tip. At this later position, enzymes are released into the environment, where the new wall material is synthesized. The rate of extension, in a favorable environment, can be extremely rapid, up to 40 m per minute. Many biophysical models ͓2-6͔ describing the growth of fungal colonies and/or single hypha have been studied. In this context, efforts focused on the nonequilibrium properties of a modification of the totally asymmetric exclusion process ͑TASEP͒, by considering a distinct dynamics of one of the two boundary sites ͓7-11͔.An important aspect not taken into account yet, is that fungi have the ability to grow in a wide range of habitats, including extreme environments ͓12-14͔ and survive intense UV/cosmic radiation during space travel ͓15͔. Since the wall of the tip is usually structurally weak ͓1͔, in such a situation the extension rate can be slowed down and as the hypha is progressively aging, it may break down or be broken by other organisms ͓1͔. Our analysis is focused on the theoretical description of the above-mentioned growing process in competition with a corrosive environment. The theoretical model used is based on a simple modification of the TASEP and captures the general behavior induced by the two competing processes.Proposed in 1968 to study the motion of ribosomes along mRNA ͓16,17͔, numerous modifications of the TASEP were introduced including multilane systems and multi species transport ͓18-22͔, Langmuir dynamics ͓23-25͔, extended particles ͓26,27͔ as well as systems with finite resources ͓28,29͔. In a general framework, such models are considered as toy models of transport phenomena in order to better understands physics far from equilibrium.In the first part of this Brief Report we define the model and the system parameters. After a careful definition of the parallel update dynami...

A thermodynamically equilibrated fluid of hard spheroids is a simple model of liquid matter. In this model, the coupling between the rotational degrees of freedom of the constituent particles and their translations may be switched off by a continuous deformation of a spheroid of aspect ratio t into a sphere (t ¼ 1). We demonstrate, by experiments, theory, and computer simulations, that dramatic nonanalytic changes in structure and thermodynamics of the fluids take place, as the coupling between rotations and translations is made to vanish. This nonanalyticity, reminiscent of a second-order liquid-liquid phase transition, is not a trivial consequence of the shape of an individual particle. Rather, free volume considerations relate the observed transition to a similar nonanalyticity at t ¼ 1 in structural properties of jammed granular ellipsoids. This observation suggests a deep connection to exist between the physics of jamming and the thermodynamics of simple fluids. DOI: 10.1103/PhysRevLett.116.098001 The thermodynamics of a fluid of simple spheres is wellknown and almost completely understood [1,2]. However, the constituents of real matter are typically nonspherical. Their translational degrees of freedom are coupled to their rotations [3]. A system of spheroids, ellipsoids of revolution, is arguably the simplest model of matter, where such a coupling exists. This model has recently been realized in colloidal and granular matter experiments, providing an important insight onto the local bulk structure of fluids [4,5] and jammed packings [6]. While a very good agreement between experiment and theory has been achieved for the fluids [5,7], these studies dealt with only one specific particle aspect ratio, t ¼ 1.6. The dependence of the fluid structure on the aspect ratio of the constituent particles has not been tested, so that the fundamental role played in these fluids by rotational degrees of freedom remains unknown. The understanding of jammed packings of ellipsoids is incomplete, as well. Many common order metrics are minimized for the, so-called, "maximally random jammed" (MRJ) packings [8]. Yet, it remains unclear, how the various protocols of compression, commonly starting from a fluidlike initial state, explore the available phase space and whether any fundamental physical reason exists for the convergence of many common compression protocols towards packings with densities close to that of the MRJ state [8][9][10][11][12][13].In this work, we study the dependence of the bulk structure in fluids of ellipsoids on the aspect ratio t ¼ a=b of the constituent particles, where a and b are the polar and the equatorial diameters, respectively. We combine experiments, theory, and Monte Carlo (MC) simulations, to explore the fundamental role of the rotational degrees of freedom in these fluids, in the vicinity of the so-called "sphere point" (t ¼ 1), where the coupling between rotations and translations vanishes. We demonstrate that the critical dependence of this coupling on ϵ ≡ jt − 1j, for ϵ → 0, gives rise...