1
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Gavazzoni C, Brito C, Wyart M. Testing Theories of the Glass Transition with the Same Liquid but Many Kinetic Rules. PHYSICAL REVIEW LETTERS 2024; 132:248201. [PMID: 38949336 DOI: 10.1103/physrevlett.132.248201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 04/23/2024] [Indexed: 07/02/2024]
Abstract
We study the glass transition by exploring a broad class of kinetic rules that can significantly modify the normal dynamics of supercooled liquids while maintaining thermal equilibrium. Beyond the usual dynamics of liquids, this class includes dynamics in which a fraction (1-f_{R}) of the particles can perform pairwise exchange or "swap moves," while a fraction f_{P} of the particles can move only along restricted directions. We find that (i) the location of the glass transition varies greatly but smoothly as f_{P} and f_{R} change and (ii) it is governed by a linear combination of f_{P} and f_{R}. (iii) Dynamical heterogeneities (DHs) are not governed by the static structure of the material; their magnitude correlates instead with the relaxation time. (iv) We show that a recent theory for temporal growth of DHs based on thermal avalanches holds quantitatively throughout the (f_{R},f_{P}) diagram. These observations are negative items for some existing theories of the glass transition, particularly those reliant on growing thermodynamic order or locally favored structure, and open new avenues to test other approaches, as we illustrate.
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Affiliation(s)
- Cristina Gavazzoni
- Instituto de Física, Universidade Federal do Rio Grande do Sul, Caixa Postal 15051, CEP 91501-970, Porto Alegre, Rio Grande do Sul, Brazil
| | - Carolina Brito
- Instituto de Física, Universidade Federal do Rio Grande do Sul, Caixa Postal 15051, CEP 91501-970, Porto Alegre, Rio Grande do Sul, Brazil
| | - Matthieu Wyart
- Institute of Physics, Ecole Polytechnique Federale de Lausanne, 729 BSP UNIL, 1015, Lausanne, Switzerland
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2
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Yang Z, Xu X, Douglas JF, Xu WS. Confinement effect of inter-arm interactions on glass formation in star polymer melts. J Chem Phys 2024; 160:044503. [PMID: 38265089 DOI: 10.1063/5.0185412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 12/25/2023] [Indexed: 01/25/2024] Open
Abstract
We utilized molecular dynamic simulation to investigate the glass formation of star polymer melts in which the topological complexity is varied by altering the number of star arms (f). Emphasis was placed on how the "confinement effect" of repulsive inter-arm interactions within star polymers influences the thermodynamics and dynamics of star polymer melts. All the characteristic temperatures of glass formation were found to progressively increase with increasing f, but unexpectedly the fragility parameter KVFT was found to decrease with increasing f. As previously observed, stars having more than 5 or 6 arms adopt an average particle-like structure that is more contracted relative to the linear polymer size having the same mass and exhibit a strong tendency for intermolecular and intramolecular segregation. We systematically analyzed how varying f alters collective particle motion, dynamic heterogeneity, the decoupling exponent ζ phenomenologically linking the slow β- and α-relaxation times, and the thermodynamic scaling index γt. Consistent with our hypothesis that the segmental dynamics of many-arm star melts and thin supported polymer films should exhibit similar trends arising from the common feature of high local segmental confinement, we found that ζ increases considerably with increasing f, as found in supported polymer films with decreasing thickness. Furthermore, increasing f led to greatly enhanced elastic heterogeneity, and this phenomenon correlates strongly with changes in ζ and γt. Our observations should be helpful in building a more rational theoretical framework for understanding how molecular topology and geometrical confinement influence the dynamics of glass-forming materials more broadly.
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Affiliation(s)
- Zhenyue Yang
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, People's Republic of China
- Academy for Advanced Interdisciplinary Studies, Northeast Normal University, Changchun 130024, People's Republic of China
| | - Xiaolei Xu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, People's Republic of China
| | - Jack F Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Wen-Sheng Xu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, People's Republic of China
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3
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Xu X, Douglas JF, Xu WS. Thermodynamic–Dynamic Interrelations in Glass-Forming Polymer Fluids. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c01511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Xiaolei Xu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
| | - Jack F. Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Wen-Sheng Xu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
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4
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Novikov VN, Sokolov AP. Temperature Dependence of Structural Relaxation in Glass-Forming Liquids and Polymers. ENTROPY (BASEL, SWITZERLAND) 2022; 24:1101. [PMID: 36010765 PMCID: PMC9407199 DOI: 10.3390/e24081101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 08/05/2022] [Accepted: 08/07/2022] [Indexed: 06/15/2023]
Abstract
Understanding the microscopic mechanism of the transition of glass remains one of the most challenging topics in Condensed Matter Physics. What controls the sharp slowing down of molecular motion upon approaching the glass transition temperature Tg, whether there is an underlying thermodynamic transition at some finite temperature below Tg, what the role of cooperativity and heterogeneity are, and many other questions continue to be topics of active discussions. This review focuses on the mechanisms that control the steepness of the temperature dependence of structural relaxation (fragility) in glass-forming liquids. We present a brief overview of the basic theoretical models and their experimental tests, analyzing their predictions for fragility and emphasizing the successes and failures of the models. Special attention is focused on the connection of fast dynamics on picosecond time scales to the behavior of structural relaxation on much longer time scales. A separate section discusses the specific case of polymeric glass-forming liquids, which usually have extremely high fragility. We emphasize the apparent difference between the glass transitions in polymers and small molecules. We also discuss the possible role of quantum effects in the glass transition of light molecules and highlight the recent discovery of the unusually low fragility of water. At the end, we formulate the major challenges and questions remaining in this field.
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Affiliation(s)
- Vladimir N. Novikov
- Institute of Automation and Electrometry, Russian Academy of Sciences, 630090 Novosibirsk, Russia
| | - Alexei P. Sokolov
- Department of Chemistry and Joint Institute for Neutron Sciences, University of Tennessee, Knoxville, TN 37996, USA
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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5
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Baba T, Kajita S, Shiga T, Ohba N. Fast evaluation technique for the shear viscosity and ionic conductivity of electrolyte solutions. Sci Rep 2022; 12:7291. [PMID: 35508564 PMCID: PMC9068762 DOI: 10.1038/s41598-022-10704-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 04/01/2022] [Indexed: 11/09/2022] Open
Abstract
With the growing need to obtain ideal materials for various applications, there is an increasing interest in computational methods to rapidly and accurately search for materials. Molecular dynamics simulation is one of the successful methods used to investigate liquid electrolytes with high transport properties applied in lithium-ion batteries. However, further reduction in computational cost is required to find a novel material with the desired properties from a large number of combinations. In this study, we demonstrate an effective fast evaluation technique for shear viscosity and ionic conductivity by molecular dynamics simulation for an exhaustive search of electrolyte materials with high transport properties. The proposed model was combined with a short-time correlation function of the stress tensor and empirical relationships to address the issues of inefficient and uncertain evaluation by conventional molecular dynamics methods. Because we focus on liquid electrolytes consisting of organic solvents and lithium salts, our model requires dissociation ratio and effective diffusion size of lithium salts. Our method is applied to search for the compositional combinations of electrolytes with superior transport properties even at low temperatures. These results correlate well with experimental results.
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Affiliation(s)
- Takeshi Baba
- Toyota Central R&D Labs., Inc., 41-1, Yokomichi, Nagakute, Aichi, 480-1192, Japan.
| | - Seiji Kajita
- Toyota Central R&D Labs., Inc., 41-1, Yokomichi, Nagakute, Aichi, 480-1192, Japan
| | - Tohru Shiga
- Toyota Central R&D Labs., Inc., 41-1, Yokomichi, Nagakute, Aichi, 480-1192, Japan
| | - Nobuko Ohba
- Toyota Central R&D Labs., Inc., 41-1, Yokomichi, Nagakute, Aichi, 480-1192, Japan
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6
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Wang X, Zhang H, Douglas JF. The initiation of shear band formation in deformed metallic glasses from soft localized domains. J Chem Phys 2021; 155:204504. [PMID: 34852471 DOI: 10.1063/5.0069729] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
It has long been thought that shear band (SB) formation in amorphous solids initiates from relatively "soft" regions in the material in which large-scale non-affine deformations become localized. The test of this hypothesis requires an effective means of identifying "soft" regions and their evolution as the material is deformed to varying degrees, where the metric of "softness" must also account for the effect of temperature on local material stiffness. We show that the mean square atomic displacement on a caging timescale ⟨u2⟩, the "Debye-Waller factor," provides a useful method for estimating the shear modulus of the entire material and, by extension, the material stiffness at an atomic scale. Based on this "softness" metrology, we observe that SB formation indeed occurs through the strain-induced formation of localized soft regions in our deformed metallic glass free-standing films. Unexpectedly, the critical strain condition for SB formation occurs when the softness (⟨u2⟩) distribution within the emerging soft regions approaches that of the interfacial region in its undeformed state, initiating an instability with similarities to the transition to turbulence. Correspondingly, no SBs arise when the material is so thin that the entire material can be approximately described as being "interfacial" in nature. We also quantify relaxation in the glass and the nature and origin of highly non-Gaussian particle displacements in the dynamically heterogeneous SB regions at times longer than the caging time.
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Affiliation(s)
- Xinyi Wang
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada
| | - Hao Zhang
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada
| | - Jack F Douglas
- Material Measurement Laboratory, Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
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7
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Lemaître A. Stress hyperuniformity and transient oscillatory-exponential correlation decay as signatures of strength vs fragility in glasses. J Chem Phys 2021; 155:194501. [PMID: 34800950 DOI: 10.1063/5.0065613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We examine and compare the local stress autocorrelation in the inherent states of a fragile and a strong glass: the Kob-Andersen (KA) binary mixture and the Beest-Kramer-Santen model of silica. For both systems, local (domain-averaged) stress fluctuations asymptotically reach the normal inverse-volume decay in the large domain limit; accordingly, the real-space stress autocorrelation presents long-range power law tails. However, in the case of silica, local stress fluctuations display a high degree of hyperuniformity, i.e., their asymptotic (normal) decay is disproportionately smaller than their bond level amplitude. This property causes the asymptotic power law tails of the real-space stress autocorrelation to be swamped, up to very large distances (several nanometers), by an intermediate oscillatory-exponential decay regime. Similar contributions exist in the KA stress autocorrelation, but they never can be considered as dominating the power law decay and fully disappear when stress is coarse-grained beyond one interatomic distance. Our observations document that the relevance of power-law stress correlation may constitute a key discriminating feature between strong and fragile glasses. Meanwhile, they highlight that the notion of local stress in atomistic systems involves by necessity a choice of observation (coarse-graining) scale, the relevant value of which depends, in principle, on both the model and the phenomenon studied.
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Affiliation(s)
- Anaël Lemaître
- Navier, Ecole des Ponts, Univ Gustave Eiffel, CNRS, Marne-la-Vallée, France
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8
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Tomoshige N, Goto S, Mizuno H, Mori T, Kim K, Matubayasi N. Understanding the scaling of boson peak through insensitivity of elastic heterogeneity to bending rigidity in polymer glasses. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:274002. [PMID: 33930889 DOI: 10.1088/1361-648x/abfd51] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 04/30/2021] [Indexed: 06/12/2023]
Abstract
Amorphous materials exhibit peculiar mechanical and vibrational properties, including non-affine elastic responses and excess vibrational states, i.e., the so-called boson peak (BP). For polymer glasses, these properties are considered to be affected by the bending rigidity of the constituent polymer chains. In our recent work [Tomoshige,et al2019,Sci. Rep.919514], we have revealed simple relationships between the variations of vibrational properties and the global elastic properties: the response of the BP scales only with that of the global shear modulus. This observation suggests that the spatial heterogeneity of the local shear modulus distribution is insensitive to changes in the bending rigidity. Here, we demonstrate the insensitivity of elastic heterogeneity by directly measuring the local shear modulus distribution. We also study transverse sound wave propagation, which is also shown to scale only with the global shear modulus. Through these analyses, we conclude that the bending rigidity does not alter the spatial heterogeneity of the local shear modulus distribution, which yields vibrational and acoustic properties that are controlled solely by the global shear modulus of a polymer glass.
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Affiliation(s)
- Naoya Tomoshige
- Division of Chemical Engineering, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Shota Goto
- Division of Chemical Engineering, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Hideyuki Mizuno
- Graduate School of Arts and Sciences, The University of Tokyo, Tokyo 153-8902, Japan
| | - Tatsuya Mori
- Department of Materials Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8573, Japan
| | - Kang Kim
- Division of Chemical Engineering, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Nobuyuki Matubayasi
- Division of Chemical Engineering, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
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9
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Giuntoli A, Puosi F, Leporini D, Starr FW, Douglas JF. Predictive relation for the α-relaxation time of a coarse-grained polymer melt under steady shear. SCIENCE ADVANCES 2020; 6:eaaz0777. [PMID: 32494635 PMCID: PMC7182423 DOI: 10.1126/sciadv.aaz0777] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 01/27/2020] [Indexed: 05/14/2023]
Abstract
We examine the influence of steady shear on structural relaxation in a simulated coarse-grained unentangled polymer melt over a wide range of temperature and shear rates. Shear is found to progressively suppress the α-relaxation process observed in the intermediate scattering function, leading ultimately to a purely inertially dominated β-relaxation at high shear rates, a trend similar to increasing temperature. On the basis of a scaling argument emphasizing dynamic heterogeneity in cooled liquids and its alteration under material deformation, we deduce and validate a parameter-free scaling relation for both the structural relaxation time τα from the intermediate scattering function and the "stretching exponent" β quantifying the extent of dynamic heterogeneity over the entire range of temperatures and shear rates that we can simulate.
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Affiliation(s)
- Andrea Giuntoli
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersbug, Maryland 20899, USA
- Department of Physics, Wesleyan University, Middletown, Connecticut 06459, USA
| | - Francesco Puosi
- Dipartimento di Fisica “Enrico Fermi,” Università di Pisa, Largo B.Pontecorvo 3, I-56127 Pisa, Italy
| | - Dino Leporini
- Dipartimento di Fisica “Enrico Fermi,” Università di Pisa, Largo B.Pontecorvo 3, I-56127 Pisa, Italy
- IPCF-CNR, UOS Pisa, Italy
| | - Francis W. Starr
- Department of Physics, Wesleyan University, Middletown, Connecticut 06459, USA
| | - Jack F. Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersbug, Maryland 20899, USA
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10
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Massa CA, Leporini D, Puosi F. Metallic glass-formers in 2D exhibit the same scaling as in 3D between vibrational dynamics and structural relaxation. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:085701. [PMID: 31675741 DOI: 10.1088/1361-648x/ab539c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Glass-forming systems approaching their glass transition exhibit universal correlations between picosecond vibrational dynamics and long-time structural relaxation, which can be described by the same master curve in the bulk or confined conditions. In this work, we study at a fundamental level the effects of the reduction of spatial dimensionality on this phenomenon. We perform molecular dynamics simulations of a metallic glass-formers in two dimensions (2D). We show that in the supercooled regime particle localization in the cage and structural relaxation are blurred by long-wavelength fluctuations specific to low-dimensional systems. Once these effects are properly removed, we demonstrate that the fast dynamics and slow relaxation comply, without any adjustment, with same scaling between the structural relaxation time and the Debye-Waller factor, originally observed in three-dimensions (3D).
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Affiliation(s)
- C A Massa
- Istituto per i Processi Chimico-Fisici-Consiglio Nazionale delle Ricerche (IPCF-CNR), via G Moruzzi 1, 56124 Pisa, Italy
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11
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Boson peak, elasticity, and glass transition temperature in polymer glasses: Effects of the rigidity of chain bending. Sci Rep 2019; 9:19514. [PMID: 31862997 PMCID: PMC6925306 DOI: 10.1038/s41598-019-55564-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Accepted: 11/29/2019] [Indexed: 11/24/2022] Open
Abstract
The excess low-frequency vibrational spectrum, called boson peak, and non-affine elastic response are the most important particularities of glasses. Herein, the vibrational and mechanical properties of polymeric glasses are examined by using coarse-grained molecular dynamics simulations, with particular attention to the effects of the bending rigidity of the polymer chains. As the rigidity increases, the system undergoes a glass transition at a higher temperature (under a constant pressure), which decreases the density of the glass phase. The elastic moduli, which are controlled by the decrease of the density and the increase of the rigidity, show a non-monotonic dependence on the rigidity of the polymer chain that arises from the non-affine component. Moreover, a clear boson peak is observed in the vibrational density of states, which depends on the macroscopic shear modulus G. In particular, the boson peak frequency ωBP is proportional to \documentclass[12pt]{minimal}
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\begin{document}$$\sqrt{G}$$\end{document}G. These results provide a positive correlation between the boson peak, shear elasticity, and the glass transition temperature.
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Tripodo A, Puosi F, Malvaldi M, Leporini D. Vibrational scaling of the heterogeneous dynamics detected by mutual information. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2019; 42:146. [PMID: 31754931 DOI: 10.1140/epje/i2019-11916-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 11/03/2019] [Indexed: 06/10/2023]
Abstract
The correlations detected by the mutual information in the propensities of a molecular viscous liquid are studied by molecular-dynamics simulations. Dynamic heterogeneity is evidenced and two particle fractions with different mobility and relaxation identified. The two fractions exhibit the scaling of their relaxation in terms of the rattling amplitude of the particle trapped in the cage of the first neighbours 〈u2〉 . The scaling master curve does not differ from the one found for bulk systems, thus confirming identical results previously reported in other systems with strong dynamic heterogeneity as thin molecular films. The excitation of planar and globular structures at short and long times with respect to structural relaxation, respectively, is revealed. Some of the globular structures are different from the ones evidenced in atomic mixtures. States with equal 〈u2〉 are found to have identical time dependence of several quantities, referring to both bulk and the two fractions with heterogeneous dynamics, at least up to the structural relaxation time [Formula: see text].
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Affiliation(s)
- Antonio Tripodo
- Dipartimento di Fisica "Enrico Fermi", Università di Pisa, Largo B. Pontecorvo 3, I-56127, Pisa, Italy
| | - Francesco Puosi
- Dipartimento di Fisica "Enrico Fermi", Università di Pisa, Largo B. Pontecorvo 3, I-56127, Pisa, Italy
| | - Marco Malvaldi
- Dipartimento di Fisica "Enrico Fermi", Università di Pisa, Largo B. Pontecorvo 3, I-56127, Pisa, Italy
| | - Dino Leporini
- Dipartimento di Fisica "Enrico Fermi", Università di Pisa, Largo B. Pontecorvo 3, I-56127, Pisa, Italy.
- IPCF-CNR, UOS, Pisa, Italy.
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13
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Puosi F, Tripodo A, Leporini D. Fast Vibrational Modes and Slow Heterogeneous Dynamics in Polymers and Viscous Liquids. Int J Mol Sci 2019; 20:ijms20225708. [PMID: 31739510 PMCID: PMC6888094 DOI: 10.3390/ijms20225708] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 11/07/2019] [Accepted: 11/08/2019] [Indexed: 11/16/2022] Open
Abstract
Many systems, including polymers and molecular liquids, when adequately cooled and/or compressed, solidify into a disordered solid, i.e., a glass. The transition is not abrupt, featuring progressive decrease of the microscopic mobility and huge slowing down of the relaxation. A distinctive aspect of glass-forming materials is the microscopic dynamical heterogeneity (DH), i.e., the presence of regions with almost immobile particles coexisting with others where highly mobile ones are located. Following the first compelling evidence of a strong correlation between vibrational dynamics and ultraslow relaxation, we posed the question if the vibrational dynamics encodes predictive information on DH. Here, we review our results, drawn from molecular-dynamics numerical simulation of polymeric and molecular glass-formers, with a special focus on both the breakdown of the Stokes-Einstein relation between diffusion and viscosity, and the size of the regions with correlated displacements.
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Affiliation(s)
- Francesco Puosi
- Dipartimento di Fisica “Enrico Fermi”, Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy; (F.P.); (A.T.)
| | - Antonio Tripodo
- Dipartimento di Fisica “Enrico Fermi”, Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy; (F.P.); (A.T.)
| | - Dino Leporini
- Dipartimento di Fisica “Enrico Fermi”, Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy; (F.P.); (A.T.)
- Istituto per i Processi Chimico-Fisici-Consiglio Nazionale delle Ricerche (IPCF-CNR), via G. Moruzzi 1, I-56124 Pisa, Italy
- Correspondence: ; Tel.: +39-050-2214937
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14
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Tripodo A, Giuntoli A, Malvaldi M, Leporini D. Mutual information does not detect growing correlations in the propensity of a model molecular liquid. SOFT MATTER 2019; 15:6784-6790. [PMID: 31406967 DOI: 10.1039/c9sm01143a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The dynamical spatial correlations detected by the mutual information (MI) in the isoconfigurational particle displacements of a monodisperse molecular viscous liquid are studied via molecular-dynamics simulations by changing considerably both the molecular mobility and the degree of dynamical heterogeneity. Different from atomic liquids, the MI correlation length does not grow on approaching the glass transition by considering the liquid both in full detail as a collection of monomers and as a coarse-grained ensemble of molecular centers of mass. In the detailed picture, it is found that: (i) the MI correlations between monomers are largely due to inter-molecular correlations, (ii) the MI length scale is numerically identical, within the errors, to the correlation length scale of the displacement direction, as drawn by conventional correlation functions. The time evolution of the MI spatial correlations complies with the scaling between the fast vibrational dynamics and the long-time relaxation. Our findings suggest that the characteristics of the MI length scale are markedly system-dependent and not obviously related to dynamical heterogeneity.
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Affiliation(s)
- Antonio Tripodo
- Dipartimento di Fisica "Enrico Fermi", Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy.
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15
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Abstract
Molecular dynamics (MD) simulations of five ionic liquids based on 1-alkyl-3-methylimidazolium cations, [C n C1im]+, have been performed in order to calculate high-frequency elastic moduli and to evaluate heterogeneity of local elastic moduli. The MD simulations of [C n C1im][NO3], n = 2, 4, 6, and 8, assessed the effect of domain segregation when the alkyl chain length increases, and [C8C1im][PF6] assessed the effect of strength of anion-cation interaction. Dispersion curves of excitation energies of longitudinal and transverse acoustic, LA and TA, modes were obtained from time correlation functions of mass currents at different wavevectors. High-frequency sound velocity of LA modes depends on the alkyl chain length, but sound velocity for TA modes does not. High-frequency bulk and shear moduli, K ∞ and G ∞ , depend on the alkyl chain length because of a density effect. Both K ∞ and G ∞ are strongly dependent on the anion. The calculation of local bulk and shear moduli was accomplished by performing bulk and shear deformations of the systems cooled to 0 K. The simulations showed a clear connection between structural and elastic modulus heterogeneities. The development of nano-heterogeneous structure with increasing length of the alkyl chain in [C n C1im][NO3] implies lower values for local bulk and shear moduli in the non-polar domains. The mean value and the standard deviations of distributions of local elastic moduli decrease when [NO3]- is replaced by the less coordinating [PF6]- anion.
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Affiliation(s)
- Arno A Veldhorst
- Laboratório de Espectroscopia Molecular, Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes 748, São Paulo 05508-000, Brazil
| | - Mauro C C Ribeiro
- Laboratório de Espectroscopia Molecular, Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes 748, São Paulo 05508-000, Brazil
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16
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Khrapak SA, Kryuchkov NP, Mistryukova LA, Khrapak AG, Yurchenko SO. Collective modes of two-dimensional classical Coulomb fluids. J Chem Phys 2018; 149:134114. [DOI: 10.1063/1.5050708] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Sergey A. Khrapak
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 82234 Weßling, Germany
| | | | | | - Alexey G. Khrapak
- Joint Institute for High Temperatures, Russian Academy of Sciences, 125412 Moscow, Russia
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17
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Chung JY, Douglas JF, Stafford CM. A wrinkling-based method for investigating glassy polymer film relaxation as a function of film thickness and temperature. J Chem Phys 2018; 147:154902. [PMID: 29055329 DOI: 10.1063/1.5006949] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
We investigate the relaxation dynamics of thin polymer films at temperatures below the bulk glass transition Tg by first compressing polystyrene films supported on a polydimethylsiloxane substrate to create wrinkling patterns and then observing the slow relaxation of the wrinkled films back to their final equilibrium flat state by small angle light scattering. As with recent relaxation measurements on thin glassy films reported by Fakhraai and co-workers, we find the relaxation time of our wrinkled films to be strongly dependent on film thickness below an onset thickness on the order of 100 nm. By varying the temperature between room temperature and Tg (≈100 °C), we find that the relaxation time follows an Arrhenius-type temperature dependence to a good approximation at all film thicknesses investigated, where both the activation energy and the relaxation time pre-factor depend appreciably on film thickness. The wrinkling relaxation curves tend to cross at a common temperature somewhat below Tg, indicating an entropy-enthalpy compensation relation between the activation free energy parameters. This compensation effect has also been observed recently in simulated supported polymer films in the high temperature Arrhenius relaxation regime rather than the glassy state. In addition, we find that the film stress relaxation function, as well as the height of the wrinkle ridges, follows a stretched exponential time dependence and the short-time effective Young's modulus derived from our modeling decreases sigmoidally with increasing temperature-both characteristic features of glassy materials. The relatively facile nature of the wrinkling-based measurements in comparison to other film relaxation measurements makes our method attractive for practical materials development, as well as fundamental studies of glass formation.
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Affiliation(s)
- Jun Young Chung
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Jack F Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Christopher M Stafford
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
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18
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Yang C, Dove MT, Brazhkin VV, Trachenko K. Yang et al. Reply. PHYSICAL REVIEW LETTERS 2018; 120:219602. [PMID: 29883149 DOI: 10.1103/physrevlett.120.219602] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Indexed: 06/08/2023]
Affiliation(s)
- C Yang
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - M T Dove
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - V V Brazhkin
- Institute for High Pressure Physics, RAS, 108840 Troitsk, Moscow, Russia
| | - K Trachenko
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
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19
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Puosi F, Pasturel A, Jakse N, Leporini D. Communication: Fast dynamics perspective on the breakdown of the Stokes-Einstein law in fragile glassformers. J Chem Phys 2018; 148:131102. [DOI: 10.1063/1.5025614] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- F. Puosi
- Grenoble INP Institute of Engineering Université Grenoble Alpes, CNRS, SIMaP, F-38000 Grenoble, France
| | - A. Pasturel
- Grenoble INP Institute of Engineering Université Grenoble Alpes, CNRS, SIMaP, F-38000 Grenoble, France
| | - N. Jakse
- Grenoble INP Institute of Engineering Université Grenoble Alpes, CNRS, SIMaP, F-38000 Grenoble, France
| | - D. Leporini
- Dipartimento di Fisica “Enrico Fermi,” Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy and IPCF-CNR, UOS, Pisa, Italy
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20
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Song J, Hsu DD, Shull KR, Phelan FR, Douglas JF, Xia W, Keten S. Energy Renormalization Method for the Coarse-Graining of Polymer Viscoelasticity. Macromolecules 2018; 51:10.1021/acs.macromol.7b02560. [PMID: 30996476 PMCID: PMC6463302 DOI: 10.1021/acs.macromol.7b02560] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Developing temperature transferable coarse-grained (CG) models is essential for the computational prediction of polymeric glass-forming (GF) material behavior, but their dynamics are often greatly altered from those of all-atom (AA) models mainly because of the reduced fluid configurational entropy under coarse-graining. To address this issue, we have recently introduced an energy renormalization (ER) strategy that corrects the activation free energy of the CG polymer model by renormalizing the cohesive interaction strength ε as a function of temperature T, i.e., ε(T), thus semiempirically preserving the T-dependent dynamics of the AA model. Here we apply our ER method to consider-in addition to T-dependency-the frequency f-dependent polymer viscoelasticity. Through smallamplitude oscillatory shear molecular dynamics simulations, we show that changing the imposed oscillation f on the CG systems requires changes in ε values (i.e., ε(T, f)) to reproduce the AA viscoelasticity. By accounting for the dynamic fragility of polymers as a material parameter, we are able to predict ε(T, f) under coarse-graining in order to capture the AA viscoelasticity, and consequently the activation energy, across a wide range of T and f in the GF regime. Specifically, we showcase our achievements on two representative polymers of distinct fragilities, polybutadiene (PB) and polystyrene (PS), and show that our CG models are able to sample viscoelasticity up to the megahertz regime, which approaches state-of-the-art experimental resolutions, and capture results sampled via AA simulations and prior experiments.
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Affiliation(s)
- Jake Song
- Department of Materials Science & Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States
| | - David D. Hsu
- Department of Physics and Engineering, Wheaton College, 501 College Avenue, Wheaton, Illinois 60187, United States
| | - Kenneth R. Shull
- Department of Materials Science & Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States
| | - Frederick R. Phelan
- Materials Science & Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Jack F. Douglas
- Materials Science & Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Wenjie Xia
- Department of Civil & Environmental Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States
- Center for Hierarchical Materials Design, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States
- Materials Science & Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Sinan Keten
- Department of Civil & Environmental Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States
- Department of Mechanical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States
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21
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Levashov VA. Contribution to viscosity from the structural relaxation via the atomic scale Green-Kubo stress correlation function. J Chem Phys 2017; 147:184502. [DOI: 10.1063/1.4991310] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Affiliation(s)
- V. A. Levashov
- Technological Design Institute of Scientific Instrument Engineering, Novosibirsk 630058, Russia
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22
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Guillaud E, Joly L, de Ligny D, Merabia S. Assessment of elastic models in supercooled water: A molecular dynamics study with the TIP4P/2005f force field. J Chem Phys 2017; 147:014504. [DOI: 10.1063/1.4991372] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Emmanuel Guillaud
- Institut Lumière Matière, CNRS, Université de Lyon, Université Claude Bernard Lyon 1, 69622 Villeurbanne, France
- Department of Materials Science, Institute of Glass and Ceramics, University of Erlangen-Nürnberg, Martensstrasse 5, 91058 Erlangen, Germany
| | - Laurent Joly
- Institut Lumière Matière, CNRS, Université de Lyon, Université Claude Bernard Lyon 1, 69622 Villeurbanne, France
| | - Dominique de Ligny
- Department of Materials Science, Institute of Glass and Ceramics, University of Erlangen-Nürnberg, Martensstrasse 5, 91058 Erlangen, Germany
| | - Samy Merabia
- Institut Lumière Matière, CNRS, Université de Lyon, Université Claude Bernard Lyon 1, 69622 Villeurbanne, France
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23
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Bernini S, Puosi F, Leporini D. Thermodynamic scaling of relaxation: insights from anharmonic elasticity. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:135101. [PMID: 28102828 DOI: 10.1088/1361-648x/aa5a7e] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Using molecular dynamics simulations of a molecular liquid, we investigate the thermodynamic scaling (TS) of the structural relaxation time [Formula: see text] in terms of the quantity [Formula: see text], where T and ρ are the temperature and density, respectively. The liquid does not exhibit strong virial-energy correlations. We propose a method for evaluating both the characteristic exponent [Formula: see text] and the TS master curve that uses experimentally accessible quantities that characterise the anharmonic elasticity and does not use details about the microscopic interactions. In particular, we express the TS characteristic exponent [Formula: see text] in terms of the lattice Grüneisen parameter [Formula: see text] and the isochoric anharmonicity [Formula: see text]. An analytic expression of the TS master curve of [Formula: see text] with [Formula: see text] as the key adjustable parameter is found. The comparison with the experimental TS master curves and the isochoric fragilities of 34 glassformers is satisfying. In a few cases, where thermodynamic data are available, we test (i) the predicted characteristic exponent [Formula: see text] and (ii) the isochoric anharmonicity [Formula: see text], as drawn by the best fit of the TS of the structural relaxation, against the available thermodynamic data. A linear relation between the isochoric fragility and the isochoric anharmonicity [Formula: see text] is found and compared favourably with the results of experiments with no adjustable parameters. A relation between the increase of the isochoric vibrational heat capacity due to anharmonicity and the isochoric fragility is derived.
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Affiliation(s)
- S Bernini
- Dipartimento di Fisica 'Enrico Fermi', Università di Pisa, Largo B Pontecorvo 3, I-56127 Pisa, Italy. Present address: Jawaharlal Nehru Center for Advanced Scientific Research, Theoretical Sciences Unit, Jakkur Campus, Bengaluru 560064, India
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24
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Wang L, Yang C, Dove MT, Fomin YD, Brazhkin VV, Trachenko K. Direct links between dynamical, thermodynamic, and structural properties of liquids: Modeling results. Phys Rev E 2017; 95:032116. [PMID: 28415224 DOI: 10.1103/physreve.95.032116] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Indexed: 06/07/2023]
Abstract
We develop an approach to liquid thermodynamics based on collective modes. We perform extensive molecular-dynamics simulations of noble, molecular, and metallic liquids, and we provide direct evidence that liquid energy and specific heat are well-described by the temperature dependence of the Frenkel (hopping) frequency. The agreement between predicted and calculated thermodynamic properties is seen in the notably wide range of temperature spanning tens of thousands of Kelvin. The range includes both subcritical liquids and supercritical fluids. We discuss the structural crossover and interrelationships between the structure, dynamics, and thermodynamics of liquids and supercritical fluids.
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Affiliation(s)
- L Wang
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - C Yang
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - M T Dove
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Yu D Fomin
- Institute for High Pressure Physics, RAS, 142190 Moscow, Russia
| | - V V Brazhkin
- Institute for High Pressure Physics, RAS, 142190 Moscow, Russia
| | - K Trachenko
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
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25
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Laurati M, Maßhoff P, Mutch KJ, Egelhaaf SU, Zaccone A. Long-Lived Neighbors Determine the Rheological Response of Glasses. PHYSICAL REVIEW LETTERS 2017; 118:018002. [PMID: 28106420 DOI: 10.1103/physrevlett.118.018002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Indexed: 05/23/2023]
Abstract
Glasses exhibit a liquidlike structure but a solidlike rheological response with plastic deformations only occurring beyond yielding. Thus, predicting the rheological behavior from the microscopic structure is difficult, but important for materials science. Here, we consider colloidal suspensions and propose to supplement the static structural information with the local dynamics, namely, the rearrangement and breaking of the cage of neighbors. This is quantified by the mean squared nonaffine displacement and the number of particles that remain nearest neighbors for a long time, i.e., long-lived neighbors, respectively. Both quantities are followed under shear using confocal microscopy and are the basis to calculate the affine and nonaffine contributions to the elastic stress, which is complemented by the viscoelastic stress to give the total stress. During start-up of shear, the model predicts three transient regimes that result from the interplay of affine, nonaffine, and viscoelastic contributions. Our prediction quantitatively agrees with rheological data and their dependencies on volume fraction and shear rate.
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Affiliation(s)
- M Laurati
- Condensed Matter Physics Laboratory, Heinrich Heine University, 40225 Düsseldorf, Germany
- División de Ciencias e Ingeniería, Universidad de Guanajuato, León 37150, Mexico
| | - P Maßhoff
- Condensed Matter Physics Laboratory, Heinrich Heine University, 40225 Düsseldorf, Germany
| | - K J Mutch
- Condensed Matter Physics Laboratory, Heinrich Heine University, 40225 Düsseldorf, Germany
| | - S U Egelhaaf
- Condensed Matter Physics Laboratory, Heinrich Heine University, 40225 Düsseldorf, Germany
| | - A Zaccone
- Department of Chemical Engineering and Biotechnology, and Cavendish Laboratory, University of Cambridge, Cambridge CB2 3RA, United Kingdom
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26
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Xia W, Song J, Jeong C, Hsu DD, Phelan FR, Douglas JF, Keten S. Energy-Renormalization for Achieving Temperature Transferable Coarse-Graining of Polymer Dynamics. Macromolecules 2017; 50:10.1021/acs.macromol.7b01717. [PMID: 30996475 PMCID: PMC6463524 DOI: 10.1021/acs.macromol.7b01717] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The bottom-up prediction of the properties of polymeric materials based on molecular dynamics simulation is a major challenge in soft matter physics. Coarse-grained (CG) models are often employed to access greater spatiotemporal scales required for many applications, but these models normally experience significantly altered thermodynamics and highly accelerated dynamics due to the reduced number of degrees of freedom upon coarse-graining. While CG models can be calibrated to meet certain properties at particular state points, there is unfortunately no temperature transferable and chemically specific coarse-graining method that allows for modeling of polymer dynamics over a wide temperature range. Here, we pragmatically address this problem by "correcting" for deviations in activation free energies that occur upon coarse-graining the dynamics of a model polymeric material (polystyrene). In particular, we propose a new strategy based on concepts drawn from the Adam-Gibbs (AG) theory of glass formation. Namely we renormalize the cohesive interaction strength and effective interaction length-scale parameters to modify the activation free energy. We show that this energy-renormalization method for CG modeling allows accurate prediction of atomistic dynamics over the Arrhenius regime, the non-Arrhenius regime of glass formation, and even the non-equilibrium glassy regime, thus allowing for the predictive modeling of dynamic properties of polymer over the entire range of glass formation. Our work provides a practical scheme for establishing temperature transferable coarse-grained models for predicting and designing the properties of polymeric materials.
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Affiliation(s)
- Wenjie Xia
- Materials Science & Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
- Department of Civil & Environmental Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States
- Center for Hierarchical Materials Design, Northwestern University, Evanston, Illinois 60208-3109, United States
| | - Jake Song
- Department of Materials Science & Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States
| | - Cheol Jeong
- Materials Science & Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - David D. Hsu
- Department of Mechanical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States
| | - Frederick R. Phelan
- Materials Science & Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Jack F. Douglas
- Materials Science & Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Sinan Keten
- Department of Civil & Environmental Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States
- Department of Mechanical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States
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27
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Puosi F, Chulkin O, Bernini S, Capaccioli S, Leporini D. Thermodynamic scaling of vibrational dynamics and relaxation. J Chem Phys 2016; 145:234904. [DOI: 10.1063/1.4971297] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- F. Puosi
- Dipartimento di Fisica “Enrico Fermi,” Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy
| | - O. Chulkin
- Dipartimento di Fisica “Enrico Fermi,” Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy
| | - S. Bernini
- Dipartimento di Fisica “Enrico Fermi,” Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy
| | - S. Capaccioli
- Dipartimento di Fisica “Enrico Fermi,” Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy
- IPCF-CNR, UOS, Pisa, Italy
| | - D. Leporini
- Dipartimento di Fisica “Enrico Fermi,” Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy
- IPCF-CNR, UOS, Pisa, Italy
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28
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Saw S, Abraham S, Harrowell P. Nonaffine displacements and the nonlinear response of a strained amorphous solid. Phys Rev E 2016; 94:022606. [PMID: 27627359 DOI: 10.1103/physreve.94.022606] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Indexed: 06/06/2023]
Abstract
We demonstrate that irreversible structural reorganization is not necessary for the observation of yield behavior in an amorphous solid. While the majority of solids strained to their yield point do indeed undergo an irreversible reorganization, we find that a significant fraction of solids exhibits yield via a reversible strain. We also demonstrate that large instantaneous strains in excess of the yield stress can result in complete stress relaxation, a result of the large nonaffine motions driven by the applied strain. The empirical similarity of the dependence of the ratio of stress over strain on the nonaffine mean-square displacement to that for the shear modulus obtained from quiescent liquid at nonzero temperature supports the proposition that rigidity depends on the size of the sampled configurational space only and is insensitive to how this space is sampled.
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Affiliation(s)
- Shibu Saw
- School of Chemistry, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Sneha Abraham
- School of Chemistry, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Peter Harrowell
- School of Chemistry, University of Sydney, Sydney, New South Wales 2006, Australia
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29
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Bernini S, Leporini D. Cage effect in supercooled molecular liquids: Local anisotropies and collective solid-like response. J Chem Phys 2016; 144:144505. [DOI: 10.1063/1.4945756] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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30
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Trachenko K, Brazhkin VV. Collective modes and thermodynamics of the liquid state. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2016; 79:016502. [PMID: 26696098 DOI: 10.1088/0034-4885/79/1/016502] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Strongly interacting, dynamically disordered and with no small parameter, liquids took a theoretical status between gases and solids with the historical tradition of hydrodynamic description as the starting point. We review different approaches to liquids as well as recent experimental and theoretical work, and propose that liquids do not need classifying in terms of their proximity to gases and solids or any categorizing for that matter. Instead, they are a unique system in their own class with a notably mixed dynamical state in contrast to pure dynamical states of solids and gases. We start with explaining how the first-principles approach to liquids is an intractable, exponentially complex problem of coupled non-linear oscillators with bifurcations. This is followed by a reduction of the problem based on liquid relaxation time τ representing non-perturbative treatment of strong interactions. On the basis of τ, solid-like high-frequency modes are predicted and we review related recent experiments. We demonstrate how the propagation of these modes can be derived by generalizing either hydrodynamic or elasticity equations. We comment on the historical trend to approach liquids using hydrodynamics and compare it to an alternative solid-like approach. We subsequently discuss how collective modes evolve with temperature and how this evolution affects liquid energy and heat capacity as well as other properties such as fast sound. Here, our emphasis is on understanding experimental data in real, rather than model, liquids. Highlighting the dominant role of solid-like high-frequency modes for liquid energy and heat capacity, we review a wide range of liquids: subcritical low-viscous liquids, supercritical state with two different dynamical and thermodynamic regimes separated by the Frenkel line, highly-viscous liquids in the glass transformation range and liquid-glass transition. We subsequently discuss the fairly recent area of liquid-liquid phase transitions, the area where the solid-like properties of liquids have become further apparent. We then discuss gas-like and solid-like approaches to quantum liquids and theoretical issues that are similar to the classical case. Finally, we summarize the emergent view of liquids as a unique system with a mixed dynamical state, and list several areas where interesting insights may appear and continue the extraordinary liquid story.
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Affiliation(s)
- K Trachenko
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
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31
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Klameth F, Vogel M. Slow Water Dynamics near a Glass Transition or a Solid Interface: A Common Rationale. J Phys Chem Lett 2015; 6:4385-4389. [PMID: 26722975 DOI: 10.1021/acs.jpclett.5b02010] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Performing molecular dynamics simulations, we investigate the enormous slowdowns of water dynamics when approaching a glass transition or a solid interface. We show that both effects can be described on common grounds within a theoretical framework, which was recently proposed by Schweizer et al. and considers coupled local hopping and elastic distortion. For confined water, we correctly describe the variation of the α-relaxation time, τα, as a function of both temperature and position with respect to the interface. Exploiting our knowledge of a cooperative length scale ξ(T) from the confinement studies, we quantitatively rationalize the glassy slowdown, τα(T), and the Stokes-Einstein breakdown of bulk water. For both confined and bulk liquid, variations of the α-relaxation time are intimately related to changes of the cage-rattling amplitude.
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Affiliation(s)
- F Klameth
- Institut für Festkörperphysik, Technische Universität Darmstadt , Hochschulstr. 6, D-64289 Darmstadt, Germany
| | - M Vogel
- Institut für Festkörperphysik, Technische Universität Darmstadt , Hochschulstr. 6, D-64289 Darmstadt, Germany
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32
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Lemaître A. Tensorial analysis of Eshelby stresses in 3D supercooled liquids. J Chem Phys 2015; 143:164515. [DOI: 10.1063/1.4933235] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
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33
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Puosi F, Leporini D. The kinetic fragility of liquids as manifestation of the elastic softening. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2015; 38:87. [PMID: 26261070 DOI: 10.1140/epje/i2015-15087-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 06/22/2015] [Accepted: 07/07/2015] [Indexed: 06/04/2023]
Abstract
We show that the fragility m , the steepness of the viscosity and relaxation time close to the vitrification, increases with the degree of elastic softening, i.e. the decrease of the elastic modulus with increasing temperature, in a universal way. This provides a novel connection between the thermodynamics, via the modulus, and the kinetics. The finding is evidenced by numerical simulations and comparison with the experimental data of glassformers with widely different fragilities (33 ≤ m ≤ 115), leading to a fragility-independent elastic master curve extending over eighteen decades in viscosity and relaxation time. The master curve is accounted for by a cavity model pointing out the roles of both the available free volume and the cage softness. A major implication of our findings is that ultraslow relaxations, hardly characterised experimentally, become predictable by linear elasticity. As an example, the viscosity of supercooled silica is derived over about fifteen decades with no adjustable parameters.
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Affiliation(s)
- F Puosi
- Dipartimento di Fisica "Enrico Fermi", Università di Pisa, Largo B. Pontecorvo 3, I-56127, Pisa, Italy
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34
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Bernini S, Leporini D. Short-time elasticity of polymer melts: Tobolsky conjecture and heterogeneous local stiffness. ACTA ACUST UNITED AC 2015. [DOI: 10.1002/polb.23783] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Sebastiano Bernini
- Dipartimento Di Fisica “Enrico Fermi”; Università di Pisa; Largo B. Pontecorvo 3 I-56127 Pisa Italy
| | - Dino Leporini
- Dipartimento Di Fisica “Enrico Fermi”; Università di Pisa; Largo B. Pontecorvo 3 I-56127 Pisa Italy
- IPCF-CNR; UOS Pisa Italy
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35
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Fuereder I, Ilg P. Influence of inherent structure shear stress of supercooled liquids on their shear moduli. J Chem Phys 2015; 142:144505. [DOI: 10.1063/1.4917042] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Affiliation(s)
- Ingo Fuereder
- Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, CH-8093 Zurich, Switzerland
| | - Patrick Ilg
- Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, CH-8093 Zurich, Switzerland
- School of Mathematical and Physical Sciences, University of Reading, Reading RG6 6AX, United Kingdom
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36
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Bernini S, Puosi F, Leporini D. Weak links between fast mobility and local structure in molecular and atomic liquids. J Chem Phys 2015; 142:124504. [PMID: 25833593 DOI: 10.1063/1.4916047] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We investigate by molecular-dynamics simulations, the fast mobility-the rattling amplitude of the particles temporarily trapped by the cage of the neighbors-in mildly supercooled states of dense molecular (linear trimers) and atomic (binary mixtures) liquids. The mixture particles interact by the Lennard-Jones potential. The non-bonded particles of the molecular system are coupled by the more general Mie potential with variable repulsive and attractive exponents in a range which is a characteristic of small n-alkanes and n-alcohols. Possible links between the fast mobility and the geometry of the cage (size and shape) are searched. The correlations on a per-particle basis are rather weak. Instead, if one groups either the particles in fast-mobility subsets or the cages in geometric subsets, the increase of the fast mobility with both the size and the asphericity of the cage is revealed. The observed correlations are weak and differ in states with equal relaxation time. Local forces between a tagged particle and the first-neighbour shell do not correlate with the fast mobility in the molecular liquid. It is concluded that the cage geometry alone is unable to provide a microscopic interpretation of the known, universal link between the fast mobility and the slow structural relaxation. We suggest that the particle fast dynamics is affected by regions beyond the first neighbours, thus supporting the presence of collective, extended fast modes.
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Affiliation(s)
- S Bernini
- Dipartimento di Fisica "Enrico Fermi," Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy
| | - F Puosi
- Laboratoire de Physique de l'École Normale Supérieure de Lyon, UMR CNRS 5672, 46 allée d'Italie, 69007 Lyon, France
| | - D Leporini
- Dipartimento di Fisica "Enrico Fermi," Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy
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37
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Kondrin MV, Brazhkin VV, Lebed YB. Fluctuation-dissipation theorem and the dielectric response in supercooled liquids. J Chem Phys 2015; 142:104505. [PMID: 25770549 DOI: 10.1063/1.4914185] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
We consider the correlation between static conductivity and dynamic dielectric relaxation in a number of polar organic liquids. Experimental evidence suggests that in the simple cases the linear dependence between characteristic frequency of relaxation process and the value of static susceptibility is observed. However, this proportionality can be broken due to the appearance of additional relaxation processes (secondary or high-frequency ones) so it can be confused with the "fractional" variant of Debye-Stokes-Einstein relation.
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Affiliation(s)
- M V Kondrin
- Institute for High Pressure Physics RAS, 142190 Troitsk, Moscow, Russia
| | - V V Brazhkin
- Institute for High Pressure Physics RAS, 142190 Troitsk, Moscow, Russia
| | - Y B Lebed
- Institute for Nuclear Research RAS, 142190 Troitsk, Moscow, Russia
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38
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Lemaître A. Structural relaxation is a scale-free process. PHYSICAL REVIEW LETTERS 2014; 113:245702. [PMID: 25541780 DOI: 10.1103/physrevlett.113.245702] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Indexed: 06/04/2023]
Abstract
We show that in deeply supercooled liquids, structural relaxation proceeds via the accumulation of Eshelby events, i.e. local rearrangements that create long-ranged and anisotropic stresses in the surrounding medium. Such events must be characterized using tensorial observables and we construct an analytical framework to probe their correlations using local stress data. By analyzing numerical simulations, we then demonstrate that events are power-law correlated in space, with a time-dependent amplitude which peaks at the alpha relaxation time τ(α). This effect, which becomes stronger near the glass transition, results from the increasingly important role of local stress fluctuations in facilitating relaxation events. Our finding precludes the existence of any length scale beyond which the relaxation process decorrelates.
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Affiliation(s)
- Anaël Lemaître
- Université Paris-Est, Laboratoire Navier (UMR 8205), CNRS, ENPC, IFSTTAR, 2 allée Képler, F-77420 Marne-la-Valle, France
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39
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Brazhkin VV, Trachenko K. Collective Excitations and Thermodynamics of Disordered State: New Insights into an Old Problem. J Phys Chem B 2014; 118:11417-27. [DOI: 10.1021/jp503647s] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- V. V. Brazhkin
- Institute
for High Pressure Physics, RAS, 142190, Moscow, Russia
| | - K. Trachenko
- School
of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, U.K
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40
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Bernini S, Puosi F, Barucco M, Leporini D. Competition of the connectivity with the local and the global order in polymer melts and crystals. J Chem Phys 2013; 139:184501. [DOI: 10.1063/1.4828725] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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41
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Chattoraj J, Lemaître A. Elastic signature of flow events in supercooled liquids under shear. PHYSICAL REVIEW LETTERS 2013; 111:066001. [PMID: 23971590 DOI: 10.1103/physrevlett.111.066001] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Revised: 03/18/2013] [Indexed: 06/02/2023]
Abstract
Using numerical simulation of a 2D Lennard-Jones system, we study the crossover from shear thinning to Newtonian flow. We find that the short-time elastic response of our system essentially does not change through this crossover, and show that, in the Newtonian regime, thermal activation triggers shear transformations, i.e., local irreversible shear events that produce Eshelby (long-ranged, anisotropic) deformation fields as previously seen in low-T glasses. Quite surprisingly, these Eshelby fields are found to persist much beyond the α-relaxation time, and shear thinning to coincide with the emergence of correlations between shear relaxation centers.
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Affiliation(s)
- Joyjit Chattoraj
- Laboratoire Navier (UMR 8205), Université Paris-Est, CNRS, ENPC, IFSTTAR, F-77420 Marne-la-Valle, France
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42
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Zaccone A, Terentjev EM. Disorder-assisted melting and the glass transition in amorphous solids. PHYSICAL REVIEW LETTERS 2013; 110:178002. [PMID: 23679782 DOI: 10.1103/physrevlett.110.178002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Indexed: 05/12/2023]
Abstract
The mechanical response of solids depends on temperature, because the way atoms and molecules respond collectively to deformation is affected at various levels by thermal motion. This is a fundamental problem of solid state science and plays a crucial role in materials science. In glasses, the vanishing of shear rigidity upon increasing temperature is the reverse process of the glass transition. It remains poorly understood due to the disorder leading to nontrivial (nonaffine) components in the atomic displacements. Our theory explains the basic mechanism of the melting transition of amorphous (disordered) solids in terms of the lattice energy lost to this nonaffine motion, compared to which thermal vibrations turn out to play only a negligible role. The theory is in good agreement with classic data on melting of amorphous polymers (for which no alternative theory can be found in the literature) and offers new opportunities in materials science.
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Affiliation(s)
- Alessio Zaccone
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
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43
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Puosi F, De Michele C, Leporini D. Scaling between relaxation, transport and caged dynamics in a binary mixture on a per-component basis. J Chem Phys 2013; 138:12A532. [DOI: 10.1063/1.4789943] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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44
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Potuzak M, Guo X, Smedskjaer MM, Mauro JC. Are the dynamics of a glass embedded in its elastic properties? J Chem Phys 2013; 138:12A501. [DOI: 10.1063/1.4730525] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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45
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Yamaguchi T, Akatsuka T, Koda S. Rheological Bases for Empirical Rules on Shear Viscosity of Lubrication Oils. J Phys Chem B 2013; 117:3232-9. [DOI: 10.1021/jp4010983] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tsuyoshi Yamaguchi
- Department of Molecular Design and Engineering, Graduate
School of Engineering, Nagoya University, Furo-cho, Chikusa, Nagoya, Aichi 464-8603, Japan
| | - Taiga Akatsuka
- Department of Molecular Design and Engineering, Graduate
School of Engineering, Nagoya University, Furo-cho, Chikusa, Nagoya, Aichi 464-8603, Japan
| | - Shinobu Koda
- Department of Molecular Design and Engineering, Graduate
School of Engineering, Nagoya University, Furo-cho, Chikusa, Nagoya, Aichi 464-8603, Japan
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46
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Sen S. Entropic vs. elastic models of fragility of glass-forming liquids: two sides of the same coin? J Chem Phys 2012; 137:164505. [PMID: 23126728 DOI: 10.1063/1.4759155] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The two most influential atomistic models that have been proposed in the literature to explain the temperature dependent activation energy of viscous flow of a glass-forming liquid, i.e., its fragility, are the configurational entropy model of Adam and Gibbs [J. Chem. Phys. 43, 139 (1965)] and the elastic "shoving" model of Dyre et al. [J. Non-Cryst. Solids 352, 4635 (2006)]. Here we demonstrate a qualitative equivalence between these two models starting from the well-established general relationships between the interatomic potentials, elastic constants, structural rearrangement, and entropy in amorphous materials. The unification of these two models provides important predictions that are consistent with experimental observations and shed new light into the problem of glass transition.
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Affiliation(s)
- Sabyasachi Sen
- Division of Materials Science, University of California at Davis, Davis, California 95616, USA
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47
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Affiliation(s)
- M. D. Ediger
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Peter Harrowell
- School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia
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48
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Abraham S, Harrowell P. The origin of persistent shear stress in supercooled liquids. J Chem Phys 2012; 137:014506. [DOI: 10.1063/1.4730912] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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49
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Fomin YD, Brazhkin VV, Ryzhov VN. Isoviscosity lines and the liquid-glass transition in simple liquids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:011503. [PMID: 23005421 DOI: 10.1103/physreve.86.011503] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Indexed: 06/01/2023]
Abstract
This article presents the study of the generic behavior of viscosity of liquids based on some simple theoretical models, the soft-spheres and Lennard-Jones systems. The use of these simple models allows us to investigate in detail the viscosity behavior in a wide range of temperatures and pressures including the high-temperature-high-pressure limits. Based on the simulation results, we discuss the shape of isoviscosity lines and analyze the glass transition at high temperatures and high pressures. Despite the fact that the viscosity drastically increases in the limit of high temperatures and high pressures along the melting line, the relaxation time rapidly decreases in this region, and the system becomes further from the glass transition.
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Affiliation(s)
- Yu D Fomin
- Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk 142190, Moscow Region, Russia
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50
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Dyre JC, Wang WH. The instantaneous shear modulus in the shoving model. J Chem Phys 2012; 136:224108. [DOI: 10.1063/1.4724102] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
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