Download or read book Molecular Dynamics Studies of Supercooled Water Using a Monatomic Model written by Emily Brooke Moore and published by . This book was released on 2012 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Molecular Dynamics Study of the Structure dynamics Relationships of Supercooled Liquids and Glasses written by Ryan Soklaski and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Central to the field of condensed matter physics is a decades old outstanding problem in the study of glasses -- namely explaining the extreme slowing of dynamics in a liquid as it is supercooled towards the so-called glass transition. Efforts to universally describe the stretched relaxation processes and heterogeneous dynamics that characteristically develop in supercooled liquids remain divided in both their approaches and successes. Towards this end, a consensus on the role that atomic and molecular structures play in the liquid is even more tenuous. However, mounting material science research efforts have culminated to reveal that the vast diversity of metallic glass species and their properties are rooted in an equally-broad set of structural archetypes. Herein lies the motivation of this dissertation: the detailed information available regarding the structure-property relationships of metallic glasses provides a new context in which one can study the evolution of a supercooled liquid by utilizing a structural motif that is known to dominate the glass. Cu_64 Zr_36 is a binary alloy whose good glass-forming ability and simple composition makes it a canonical material to both empirical and numerical studies. Here, we perform classical molecular dynamics simulations and conduct a comprehensive analysis of the dynamical regimes of liquid Cu_64 Zr_36, while focusing on the roles played by atomic icosahedral ordering -- a structural motif which ultimately percolates the glass' structure. Large data analysis techniques are leveraged to obtain uniquely detailed structural and dynamical information in this context. In doing so, we develop the first account of the origin of icosahedral order in this alloy, revealing deep connections between this incipient structural ordering, frustration-limited domain theory, and recent important empirical findings that are relevant to the nature of metallic liquids at large. Furthermore, important dynamical landmarks such as the breakdown of the Stokes-Einstein relationship, the decoupling of particle diffusivities, and the development of general "glassy" relaxation features are found to coincide with successive manifestation of icosahedral ordering that arise as the liquid is supercooled. Remarkably, we detect critical-like features in the growth of the icosahedron network, with signatures that suggest that a liquid-liquid phase transition may occur in the deeply supercooled regime to precede glass formation. Such a transition is predicted to occur in many supercooled liquids, although explicit evidence of this phenomenon in realistic systems is scarce. Ultimately this work concludes that icosahedral order characterizes all dynamical regimes of Cu_64 Zr_36, demonstrating the importance and utility of studying supercooled liquids in the context of locally-preferred structure. More broadly, it serves to confirm and inform recent theoretical and empirical findings that are central to understanding the physics underlying the glass transition
Download or read book Effects of Confinement on the Thermodynamics of Supercooled Water written by and published by . This book was released on 2012 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The main focus of this thesis is to understand how confinement alters the phase diagram of supercooled liquid water by employing methods of statistical mechanics and numerical simulations.Water is very complex and anomalous when compared to simple liquids. For example, experimental data for liquid water reveals the presence of a temperature of maximum density (TMD) below which the density decreases under isobaric cooling. Another anomaly is the hypothesized liquid-liquid phase transition (LLPT) between two types of liquid water with different densities. In this thesis we study how confinement affects such anomalies as TMD and LLPT in supercooled liquid water.This thesis is separated into three parts: (i) Monte Carlo simulations of a 2D coarse-grained model of a water layer confined in a fixed disordered matrix of hydrophobic nanoparticles, (ii) molecular dynamics simulations of a Jagla ramp model of liquid confined in fixed ordered and disordered matrices of hydrophobic nanoparticles, and (iii) all-atom simulations of trehalose and maltose in aqueous solution of lysozyme.In Part (i), we perform Monte Carlo simulations and find that a nanoparticle concentration as small as 2.4% is enough to destroy the LLPT for pressure P > 0.14 GPa. Moreover, we find a substantial (more than 90%) decrease of compressibility, thermal expansion coefficient and specific heat at high P and low temperature T upon increase of nanoparticle concentration from 0% to 25%.In Part (ii), we ask how, for single component systems interacting via a soft-core isotropic potential with two characteristic length scales, the geometry of hydrophobic confinement affects the phase diagram. We use molecular dynamics simulations to study particles interacting through a ramp potential and a shoulder potential, each confined in a fixed matrix of nanoscopic particles with a fixed volume fraction. We find a substantial weakening of the LLPT and the disappearance of TMD upon the increase of disorder in the confining geometry.In Part (iii), we study aqueous systems with all-atom simulations. We are currently investigating the mechanism of water-trehalose-protein and water-maltose-protein interaction upon supercooling for its relevance to bioprotection.
Download or read book From Brownian Motion to Supercooled Water in Confinements a Molecular Dynamics Simulation Study written by Felix Klameth and published by . This book was released on 2015 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Supercooled Liquids written by John T. Fourkas and published by . This book was released on 1997 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents some of the most exciting recent work on supercooled liquids. Topics include domain models of supercooled liquids, inhomogeneity and polymorphism, and Mode-Coupling Theory and its applications. It provides in-depth coverage of supercooled water and of the connections between supercooled liquids and the conformational dynamics of proteins. The introduction includes a detailed discussion of terminology, major problems, and leading theoretical and experimental approaches.
Download or read book Advances in Computer Simulation Studies on Crystal Growth written by Hiroki Nada and published by MDPI. This book was released on 2018-11-16 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a printed edition of the Special Issue "Advances in Computer Simulation Studies on Crystal Growth" that was published in Crystals
Download or read book Study of Slow Dynamics in Supercooled Water by Molecular Dynamics and Quasi elastic Neutron Scattering written by Li Liu (Ph. D.) and published by . This book was released on 2005 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Cont.) We observe a clear evidence of a cusp-like F-S dynamic transition at pressures lower than 1600 bar. Here we show that the transition temperature decreases steadily with an increasing pressure, until it intersects the homogeneous nucleation temperature line of bulk water at a pressure of 1600 bar. Above this pressure, it is no longer possible to discern the characteristic feature of the F-S transition. The discussion part of this thesis concludes that the high-temperature liquid corresponds to the high-density liquid (HDL) of which the hydrogen bond network is not fully developed to conform a locally tetrahedral coordination, while the low-temperature liquid corresponds to the low-density liquid (LDL) of which the more open, locally 4-coordinated, ice-like hydrogen bond network is fully developed. Identification of the end point of F-S transition with a possible second critical point is also discussed.
Download or read book Molecular Dynamics Studies of Surface Dynamics and Dynamic Heterogeneity of Supercooled Metallic Liquid written by Yanqin Zhai and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Studies of Liquid liquid Phase Transition and Critical Phenomena in Supercooled Confined Water by Neutron Scattering written by Dazhi Liu (Ph. D.) and published by . This book was released on 2008 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: Small angle neutron scattering (SANS) is used to measure the density of water contained in 1-D cylindrical pores of a mesoporous silica material MCM-41-S. By being able to suppress the homogenous nucleation process inside the narrow pore, one can keep water in the liquid state down to at least 160 K. We observe a density minimum at 210±5 K. This is the first experimental evidence of the existence of the density minimum in supercooled water. We show that the results are consistent with the predictions of molecular dynamics simulations of supercooled bulk water. From a combined analysis of SANS data from both H20 and D20 hydrated samples, we determined the absolute value of the density of water in the 1-D confined geometry. We found that the average density of water inside the fully hydrated MCM-41-S is higher than that of the bulk water. Pore size and hydration level dependences of the density are also studied. The temperature derivative of the density shows a pronounced peak signaling the crossing of the Widom line and confirming the existence of a liquid-liquid critical point at an elevated pressure.
Download or read book Thermodynamics and Dynamics of Supercooled Water written by Marco G. Mazza and published by . This book was released on 2009 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: This thesis employs methods of statistical mechanics and numerical simulations to study some aspects of the thermodynamic and dynamic behavior of liquid water. As liquid water is cooled down into the supercooled state, some regions of the sample show correlated molecular motion. Previously, only the translational motion has been the object of investigation. Given the importance of orientational dynamics for water, a question that naturally arises is whether the rotational molecular motion also shows heterogeneous dynamics. We show that the most rotationally mobile molecules tend to form clusters, "rotational heterogeneities", and we study their dependence upon observation time and temperature. Further, we show evidence that molecules belonging to dynamic heterogeneities are involved in bifurcated bonds. Since the presence of dynamic heterogeneities is increasingly important as the temperature is lowered, one would expect a signature of this phenomenon in dynamical quantities. We study the effect of dynamic heterogeneities on the origin of the breakdown of the Stokes-- Einstein and Stokes--Einstein--Debye relations for water. These relations link the diffusivity to temperature and viscosity. We study the separation of time scales of dynamic heterogeneities and the diffusive regime. We also consider different sets of mobility, slowest and fastest, for both translational and rotational heterogeneities. A long-standing problem in biology is the seemingly universal loss of biological activity of all biomolecules, a phenomenon termed the "protein glass transition". We explore the connection between the hypothesized liquid-liquid phase transition of water, and the protein glass transition. We find that the protein glass transition coincides with the crossing of the Widom line of hydration water. Many different scenarios have been proposed to rationalize water's thermodynamic anomalies. We study a tell model for water using the Wolff' cluster algorithm, which permits rapid equilibration. We find that three different scenarios for the phase diagram of water can be coherently described through the concept of H bond cooperativity. Finally, we study an intriguing prediction of the tell model: the presence of two maxima in the specific heat of water. We draw connections with recent experimental data.
Download or read book Journal of Research of the National Bureau of Standards written by United States. National Bureau of Standards and published by . This book was released on 1988 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dynamic Anomalies in a Supercooled Liquid written by and published by . This book was released on 1990 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dynamic Susceptibility in a Supercooled Liquid written by and published by . This book was released on 1990 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Thermodynamics and Dynamics of Supercooled Water written by Kevin C. Stokely and published by . This book was released on 2013 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: This thesis utilizes the methods of statistical physics and computer simulation to study the thermodynamic and dynamic behavior of liquid water at supercooled temperatures.The behavior of water deviates from that of a simple liquid in a number of remarkable ways, many of which become more apparent as the liquid is supercooled below its equilibrium freezing temperature. Yet, due to nucleation to the crystalline state, a large region of the phase diagram of the supercooled liquid remains unexplored.We make use of a simple model for liquid water to shed light on the behavior of real water in the experimentally inaccessible region. The model predicts a line of phase transitions in the pressure--temperature plane, between high- and low-density forms of liquid water, ending in a liquid-liquid critical point (LLCP). Such a LLCP provides a thermodynamic origin for one of liquid water's anomalies--the rapid rise, and extrapolated divergence, of thermodynamic response functions upon cooling.We find one such response function, the isobaric specific heat, CP , displays two distinct maxima as a function of temperature T in the supercooled region. One maximum is a consequence of the directional nature of hydrogen (H) bonding among molecules; the other is a consequence of the cooperative nature of H bonding. With pressurization, these two maxima move closer in T, finally coinciding at the LLCP. This suggests that measurement of CP far from any LLCP could provide evidence for the existence of water's LLCP.Recent experiments find that the T- dependence of the characteristic time for H bond rearrangement displays three distinct regimes. Our observed behavior of CP , combined with Adam-Gibbs theory, allows for a thermodynamic interpretation of this feature of water's dynamics. The dynamics of the model are also measured directly by a Monte Carlo procedure, and are found in agreement with experiment.Further, the model allows the directional and cooperative components of the H bond interaction to be varied independently. By varying only these two energy scales, the low-T phase diagram changes dramatically, exhibiting one of several previously proposed thermodynamic scenarios. Our results link each of these scenarios, by recognizing the energetics of the H bond as the underlying physical mechanism responsible for each.
Download or read book Water and Aqueous Solutions at Subzero Temperatures written by Felix Franks and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 495 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Volume, the last of the series, is devoted to water in its metastable forms, especially at sub-zero temperatures. The past few years have wit nessed an increasing interest in supercooled water and amorphous ice. If the properties of liquid water in the normal temperature range are already eccentric, then they become exceedingly so below the normal freezing point, in the metastable temperature range. Water can be supercooled to -39°C without too much effort, and most of its physical properties show a re markable temperature dependence under these conditions. Although ade quate explanations are still lacking, the time has come to review available knowledge. The study of amorphous ice, that is, the solid formed when water vapor is condensed on a very cold surface, is of longer standing. It has achieved renewed interest because it may serve as a model for the liquid state. There is currently a debate whether or not a close structural relation ship exists between amorphous ice and supercooled water. The nucleation and growth of ice in supercooled water and aqueous solutions is also still one of those grey areas of research, although these topics have received considerable attention from chemists and physicists over the past two decades. Even now, the relationships between degree of supercooling, nucleation kinetics, crystal growth kinetics, cooling rate and solute concentration are somewhat obscure. Nevertheless, at the empirical level much progress has been made, because these topics are of considerable importance to biologists, technologists, atmospheric physicists and gla ciologists.
Download or read book Water in Biological and Chemical Processes written by Biman Bagchi and published by Cambridge University Press. This book was released on 2013-11-14 with total page 383 pages. Available in PDF, EPUB and Kindle. Book excerpt: A unified overview of the dynamical properties of water and its unique and diverse role in biological and chemical processes.
Download or read book Metastable Liquids written by Pablo G. Debenedetti and published by Princeton University Press. This book was released on 2020-06-16 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metastable Liquids provides a comprehensive treatment of the properties of liquids under conditions where the stable state is a vapor, a solid, or a liquid mixture of different composition. It examines the fundamental principles that govern the equilibrium properties, stability, relaxation mechanisms, and relaxation rates of metastable liquids. Building on the interplay of kinetics and thermodynamics that determines the thermophysical properties and structural relaxation of metastable liquids, it offers an in-depth treatment of thermodynamic stability theory, the statistical mechanics of metastability, nucleation, spinodal decomposition, supercooled liquids, and the glass transition. Both traditional topics--such as stability theory--and modern developments--including modern theories of nucleation and the properties of supercooled and glassy water--are treated in detail. An introductory chapter illustrates, with numerous examples, the importance and ubiquity of metastable liquids. Examples include the ascent of sap in plants, the strategies adopted by many living organisms to survive prolonged exposure to sub-freezing conditions, the behavior of proteins at low temperatures, metastability in mineral inclusions, ozone depletion, the preservation and storage of labile biochemicals, and the prevention of natural gas clathrate hydrate formation. All mathematical symbols are defined in the text and key equations are clearly explained. More complex mathematical explanations are available in the appendixes.
