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Longo TJ, Anisimov MA. Phase transitions affected by natural and forceful molecular interconversion. J Chem Phys 2022; 156:084502. [DOI: 10.1063/5.0081180] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
If a binary liquid mixture, composed of two alternative species with equal amounts, is quenched from a high temperature to a low temperature, below the critical point of demixing, then the mixture will phase separate through a process known as spinodal decomposition. However, if the two alternative species are allowed to interconvert, either naturally (e.g., the equilibrium interconversion of enantiomers) or forcefully (e.g., via an external source of energy or matter), then the process of phase separation may drastically change. In this case, depending on the nature of interconversion, two phenomena could be observed: either phase amplification, the growth of one phase at the expense of another stable phase, or microphase separation, the formation of nongrowing (steady-state) microphase domains. In this work, we phenomenologically generalize the Cahn–Hilliard theory of spinodal decomposition to include the molecular interconversion of species and describe the physical properties of systems undergoing either phase amplification or microphase separation. We apply the developed phenomenology to accurately describe the simulation results of three atomistic models that demonstrate phase amplification and/or microphase separation. We also discuss the application of our approach to phase transitions in polyamorphic liquids. Finally, we describe the effects of fluctuations of the order parameter in the critical region on phase amplification and microphase separation.
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Affiliation(s)
- Thomas J. Longo
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, USA
| | - Mikhail A. Anisimov
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, USA
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland 20742, USA
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2
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Horstmann R, Vogel M. Relations between thermodynamics, structures, and dynamics for modified water models in their supercooled regimes. J Chem Phys 2021; 154:054502. [DOI: 10.1063/5.0037080] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Affiliation(s)
- R. Horstmann
- Institute of Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstr. 6, 64289 Darmstadt, Germany
| | - M. Vogel
- Institute of Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstr. 6, 64289 Darmstadt, Germany
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3
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Williamson NH, Dower AM, Codd SL, Broadbent AL, Gross D, Seymour JD. Glass Dynamics and Domain Size in a Solvent-Polymer Weak Gel Measured by Multidimensional Magnetic Resonance Relaxometry and Diffusometry. PHYSICAL REVIEW LETTERS 2019; 122:068001. [PMID: 30822092 PMCID: PMC6546293 DOI: 10.1103/physrevlett.122.068001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 11/07/2018] [Indexed: 05/08/2023]
Abstract
Nuclear magnetic resonance measurements of rotational and translational molecular dynamics are applied to characterize the nanoscale dynamic heterogeneity of a physically cross-linked solvent-polymer system above and below the glass transition temperature. Measured rotational dynamics identify domains associated with regions of solidlike and liquidlike dynamics. Translational dynamics provide quantitative length and timescales of nanoscale heterogeneity due to polymer network cross-link density. Mean squared displacement measurements of the solvent provide microrheological characterization of the system and indicate glasslike caging dynamics both above and below the glass transition temperature.
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Affiliation(s)
- Nathan H. Williamson
- Department of Chemical and Biological Engineering Montana State University, Bozeman, Montana 59717-3920, USA
| | - April M. Dower
- Department of Chemical and Biological Engineering Montana State University, Bozeman, Montana 59717-3920, USA
| | - Sarah L. Codd
- Department of Mechanical and Industrial Engineering, Montana State University, Bozeman, Montana 59717, USA
| | | | | | - Joseph D. Seymour
- Department of Chemical and Biological Engineering Montana State University, Bozeman, Montana 59717-3920, USA
- Corresponding author.
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4
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Geske J, Harrach M, Heckmann L, Horstmann R, Klameth F, Müller N, Pafong E, Wohlfromm T, Drossel B, Vogel M. Molecular Dynamics Simulations of Water, Silica, and Aqueous Mixtures in Bulk and Confinement. ACTA ACUST UNITED AC 2018. [DOI: 10.1515/zpch-2017-1042] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Abstract
Aqueous systems are omnipresent in nature and technology. They show complex behaviors, which often originate in the existence of hydrogen-bond networks. Prominent examples are the anomalies of water and the non-ideal behaviors of aqueous solutions. The phenomenology becomes even richer when aqueous liquids are subject to confinement. To this day, many properties of water and its mixtures, in particular, under confinement, are not understood. In recent years, molecular dynamics simulations developed into a powerful tool to improve our knowledge in this field. Here, our simulation results for water and aqueous mixtures in the bulk and in various confinements are reviewed and some new simulation data are added to improve our knowledge about the role of interfaces. Moreover, findings for water are compared with results for silica, exploiting that both systems form tetrahedral networks.
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Affiliation(s)
- Julian Geske
- Institut für Festkörperphysik , Technische Universität Darmstadt, Hochschulstr. 6 , 64289 Darmstadt , Germany
| | - Michael Harrach
- Institut für Festkörperphysik , Technische Universität Darmstadt, Hochschulstr. 6 , 64289 Darmstadt , Germany
| | - Lotta Heckmann
- Institut für Festkörperphysik , Technische Universität Darmstadt, Hochschulstr. 6 , 64289 Darmstadt , Germany
| | - Robin Horstmann
- Institut für Festkörperphysik , Technische Universität Darmstadt, Hochschulstr. 6 , 64289 Darmstadt , Germany
| | - Felix Klameth
- Institut für Festkörperphysik , Technische Universität Darmstadt, Hochschulstr. 6 , 64289 Darmstadt , Germany
| | - Niels Müller
- Institut für Festkörperphysik , Technische Universität Darmstadt, Hochschulstr. 6 , 64289 Darmstadt , Germany
| | - Elvira Pafong
- Institut für Festkörperphysik , Technische Universität Darmstadt, Hochschulstr. 6 , 64289 Darmstadt , Germany
| | - Timothy Wohlfromm
- Institut für Festkörperphysik , Technische Universität Darmstadt, Hochschulstr. 6 , 64289 Darmstadt , Germany
| | - Barbara Drossel
- Institut für Festkörperphysik , Technische Universität Darmstadt, Hochschulstr. 6 , 64289 Darmstadt , Germany
| | - Michael Vogel
- Institut für Festkörperphysik , Technische Universität Darmstadt, Hochschulstr. 6 , 64289 Darmstadt , Germany
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5
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Pafong Sanjon E, Drossel B, Vogel M. Effects of the bond polarity on the structural and dynamical properties of silica-like liquids. J Chem Phys 2018; 148:104506. [PMID: 29544292 DOI: 10.1063/1.5017681] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Silica is a network-forming liquid that shares many properties with water due to its tetrahedral structure. It undergoes a transition from a fragile to a strong liquid as the temperature is decreased, which is accompanied by a structural change to lower density and higher tetrahedral order. In order to disentangle the effects of Coulomb and van der Waals interactions on the structure and dynamics of liquid silica, we modify the bond polarity by changing the partial charges assigned to each atom. Using molecular dynamics simulations, we show that density, tetrahedral order, and structural relaxation times decrease when reducing bond polarity. Moreover, we find that the density maximum and the fragile-to-strong transition move to lower temperatures until they eventually vanish when the partial charges are decreased below approximately 75% of their regular value. Irrespective of whether strong or fragile behavior exists, structural relaxation is governed by hopping motion at sufficiently low temperatures. As long as there is a strong regime, the energy barrier associated with strong dynamics decreases with decreasing partial charges, but the dependence on the bond polarity differs from that of the activation energy in the Arrhenius regime at high temperatures. We show that the fragile-to-strong transition is associated with structural changes occurring between the first and second coordination shells that lead to a decrease in density and an increase in tetrahedral order. In particular, independent of the value of the partial charges, the distribution of the local structures is the same at this dynamic crossover, but we find no evidence that the effect occurs upon crossing the Widom line. In the fragile regime at intermediate temperatures, the relaxation times are well described by a previously proposed model which decomposes the apparent activation energy into a constant single-particle contribution and a temperature-dependent collective contribution. However, our results for silica-like melts do not obey several common relations of the model parameters reported for molecular glass formers.
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Affiliation(s)
- E Pafong Sanjon
- Institut für Festkörperphysik, Technische Universität Darmstadt, Hochschulstr. 6, 64289 Darmstadt, Germany
| | - B Drossel
- Institut für Festkörperphysik, Technische Universität Darmstadt, Hochschulstr. 6, 64289 Darmstadt, Germany
| | - M Vogel
- Institut für Festkörperphysik, Technische Universität Darmstadt, Hochschulstr. 6, 64289 Darmstadt, Germany
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6
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Flores-Ruiz H, Micoulaut M. From elemental tellurium to Ge 2Sb 2Te 5 melts: High temperature dynamic and relaxation properties in relationship with the possible fragile to strong transition. J Chem Phys 2018; 148:034502. [PMID: 29352786 DOI: 10.1063/1.5013668] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We investigate the dynamic properties of Ge-Sb-Te phase change melts using first principles molecular dynamics with a special emphasis on the effect of tellurium composition on melt dynamics. From structural models and trajectories established previously [H. Flores-Ruiz et al., Phys. Rev. B 92, 134205 (2015)], we calculate the diffusion coefficients for the different species, the activation energies for diffusion, the Van Hove correlation, and the intermediate scattering functions able to substantiate the dynamics and relaxation behavior of the liquids as a function of temperature and composition that is also compared to experiment whenever possible. We find that the diffusion is mostly Arrhenius-like and that the addition of Ge/Sb atoms leads to a global decrease of the jump probability and to an increase in activated dynamics for diffusion. Relaxation behavior is analyzed and used in order to evaluate the possibility of a fragile to strong transition that is evidenced from the calculated high fragility (M = 129) of Ge2Sb2Te5 at high temperatures.
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Affiliation(s)
- H Flores-Ruiz
- Laboratoire de Physique Théorique de la Matière Condensée, Paris Sorbonne Universités - UPMC, Boite 121, 4, Place Jussieu, 75252 Paris Cedex 05, France
| | - M Micoulaut
- Laboratoire de Physique Théorique de la Matière Condensée, Paris Sorbonne Universités - UPMC, Boite 121, 4, Place Jussieu, 75252 Paris Cedex 05, France
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7
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Geske J, Drossel B, Vogel M. Structure and dynamics of a silica melt in neutral confinement. J Chem Phys 2017; 146:134502. [DOI: 10.1063/1.4979341] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Julian Geske
- Institut für Festkörperphysik, Technische Universität Darmstadt, Hochschulstraße 6, 64289 Darmstadt, Germany
| | - Barbara Drossel
- Institut für Festkörperphysik, Technische Universität Darmstadt, Hochschulstraße 6, 64289 Darmstadt, Germany
| | - Michael Vogel
- Institut für Festkörperphysik, Technische Universität Darmstadt, Hochschulstraße 6, 64289 Darmstadt, Germany
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8
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Vollmayr-Lee K, Gorman CH, Castillo HE. Universal scaling in the aging of the strong glass former SiO2. J Chem Phys 2016; 144:234510. [PMID: 27334182 DOI: 10.1063/1.4953911] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We show that the aging dynamics of a strong glass former displays a strikingly simple scaling behavior, connecting the average dynamics with its fluctuations, namely, the dynamical heterogeneities. We perform molecular dynamics simulations of SiO2 with van Beest-Kramer-van Santen interactions, quenching the system from high to low temperature, and study the evolution of the system as a function of the waiting time tw measured from the instant of the quench. We find that both the aging behavior of the dynamic susceptibility χ4 and the aging behavior of the probability distribution P(fs,r) of the local incoherent intermediate scattering function fs,r can be described by simple scaling forms in terms of the global incoherent intermediate scattering function C. The scaling forms are the same that have been found to describe the aging of several fragile glass formers and that, in the case of P(fs,r), have been also predicted theoretically. A thorough study of the length scales involved highlights the importance of intermediate length scales. We also analyze directly the scaling dependence on particle type and on wavevector q and find that both the average and the fluctuations of the slow aging dynamics are controlled by a unique aging clock, which is not only independent of the wavevector q, but is also the same for O and Si atoms.
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Affiliation(s)
- Katharina Vollmayr-Lee
- Department of Physics and Astronomy, Bucknell University, Lewisburg, Pennsylvania 17837, USA
| | - Christopher H Gorman
- Department of Mathematics, University of California, Santa Barbara, California 93106, USA
| | - Horacio E Castillo
- Department of Physics and Astronomy and Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701, USA
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9
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Lascaris E. Tunable Liquid-Liquid Critical Point in an Ionic Model of Silica. PHYSICAL REVIEW LETTERS 2016; 116:125701. [PMID: 27058086 DOI: 10.1103/physrevlett.116.125701] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Indexed: 06/05/2023]
Abstract
Recently, it was shown that the Woodcock-Angell-Cheeseman model for liquid silica [L. V. Woodcock, C. A. Angell, and P. Cheeseman, J. Chem. Phys. 65, 1565 (1976)] is remarkably close to having a liquid-liquid critical point (LLCP). We demonstrate that increasing the ion charge separates the global maxima of the response functions, while reducing the charge smoothly merges them into a LLCP, a phenomenon that might be experimentally observable with charged colloids. An analysis of the Si and O coordination numbers suggests that a sufficiently low Si/O coordination number ratio is needed to attain a LLCP.
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Affiliation(s)
- Erik Lascaris
- Center for Polymer Studies and Department of Physics, Boston University, Boston, Massachusetts 02215, USA
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10
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Bertolazzo AA, Kumar A, Chakravarty C, Molinero V. Water-like Anomalies and Phase Behavior of a Pair Potential that Stabilizes Diamond. J Phys Chem B 2015; 120:1649-59. [DOI: 10.1021/acs.jpcb.5b08432] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Andressa A. Bertolazzo
- Department of Chemistry, The University of Utah, Salt Lake City, Utah 84112-0850, United States
- Department of Chemistry, Indian Institute of Technology-Delhi, New Delhi 110016, India
| | - Abhinaw Kumar
- Department of Chemistry, The University of Utah, Salt Lake City, Utah 84112-0850, United States
- Department of Chemistry, Indian Institute of Technology-Delhi, New Delhi 110016, India
| | - Charusita Chakravarty
- Department of Chemistry, The University of Utah, Salt Lake City, Utah 84112-0850, United States
- Department of Chemistry, Indian Institute of Technology-Delhi, New Delhi 110016, India
| | - Valeria Molinero
- Department of Chemistry, The University of Utah, Salt Lake City, Utah 84112-0850, United States
- Department of Chemistry, Indian Institute of Technology-Delhi, New Delhi 110016, India
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