1
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Adžić N, Jochum C, Likos CN, Stiakakis E. Engineering Ultrasoft Interactions in Stiff All-DNA Dendrimers by Site-Specific Control of Scaffold Flexibility. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2308763. [PMID: 38183376 DOI: 10.1002/smll.202308763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Revised: 12/10/2023] [Indexed: 01/08/2024]
Abstract
A combined experimental and theoretical study of the structural correlations in moderately concentrated suspensions of all-DNA dendrimers of the second generation (G2) with controlled scaffold rigidity is reported here. Small-angle X-ray scattering experiments in concentrated aqueous saline solutions of stiff all-DNA G2 dendritic constructs reveal a novel anomalous liquid-like phase behavior which is reflected in the calculated structure factors as a two-step increase at low scattering wave vectors. By developing a new design strategy for adjusting the particle's internal flexibility based on site-selective incorporation of single-stranded DNA linkers into the dendritic scaffold, it is shown that this unconventional type of self-organization is strongly contingent on the dendrimer's stiffness. A comprehensive computer simulation study employing dendritic models with different levels of coarse-graining, and two theoretical approaches based on effective, pair-potential interactions, remarkably confirmed the origin of this unusual liquid-like behavior. The results demonstrate that the precise control of the internal structure of the dendritic scaffold conferred by the DNA can be potentially used to engineer a rich palette of novel ultrasoft interaction potentials that could offer a route for directed self-assembly of intriguing soft matter phases and experimental realizations of a host of unusual phenomena theoretically predicted for ultrasoft interacting systems.
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Affiliation(s)
- Nataša Adžić
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, Vienna, A-1090, Austria
- Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, Belgrade, 11080, Serbia
| | - Clemens Jochum
- Institute for Theoretical Physics, TU Wien, Wiedner Hauptstraße 8-10, Vienna, A-1040, Austria
| | - Christos N Likos
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, Vienna, A-1090, Austria
| | - Emmanuel Stiakakis
- Biomacromolecular Systems and Processes, Institute of Biological Information Processing (IBI-4), Forschungszentrum Jülich, D-52425, Jülich, Germany
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2
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Yu N, Huang D, Lu S, Khrapak S, Feng Y. Universal scaling of transverse sound speed and its isomorphic property in Yukawa fluids. Phys Rev E 2024; 109:035202. [PMID: 38632806 DOI: 10.1103/physreve.109.035202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2024] [Accepted: 02/13/2024] [Indexed: 04/19/2024]
Abstract
Molecular dynamical simulations are performed to investigate the scaling of the transverse sound speed in two-dimensional (2D) and 3D Yukawa fluids. From the calculated diagnostics of the radial distribution function, the mean-squared displacement, and the Pearson correlation coefficient, the approximate isomorphic curves for 2D and 3D liquidlike Yukawa systems are obtained. It is found that the structure and dynamics of 2D and 3D liquidlike Yukawa systems exhibit the isomorphic property under the conditions of the same relative coupling parameter Γ/Γ_{m}=const. It is demonstrated that the reduced transverse sound speed, i.e., the ratio of the transverse sound speed to the thermal speed, is an isomorph invariant, which is a quasiuniversal function of Γ/Γ_{m}. The obtained isomorph invariant of the reduced transverse sound speed can be useful to estimate the transverse sound speed, or determine the coupling strength, with applications to dusty (complex) plasma or colloidal systems.
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Affiliation(s)
- Nichen Yu
- Institute of Plasma Physics and Technology, School of Physical Science and Technology, Jiangsu Key Laboratory of Thin Films, Soochow University, Suzhou 215006, China
| | - Dong Huang
- Institute of Plasma Physics and Technology, School of Physical Science and Technology, Jiangsu Key Laboratory of Thin Films, Soochow University, Suzhou 215006, China
| | - Shaoyu Lu
- Institute of Plasma Physics and Technology, School of Physical Science and Technology, Jiangsu Key Laboratory of Thin Films, Soochow University, Suzhou 215006, China
| | - Sergey Khrapak
- Joint Institute for High Temperatures, Russian Academy of Sciences, 125412 Moscow, Russia
| | - Yan Feng
- Institute of Plasma Physics and Technology, School of Physical Science and Technology, Jiangsu Key Laboratory of Thin Films, Soochow University, Suzhou 215006, China
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3
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Suzuki R, Chiba K, Tanaka S, Okuyama K. Electronic spectra of jet-cooled 1,4-bis(phenylethynyl)benzene: Strength in π-electron conjugation and two large-amplitude torsional motions. J Chem Phys 2024; 160:024301. [PMID: 38189806 DOI: 10.1063/5.0176162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 10/30/2023] [Indexed: 01/09/2024] Open
Abstract
To spectroscopically qualify strength in the π-electron conjugation, the electronic spectra of jet-cooled 1,4-bis(phenylethynyl)benzene (BPEB) in the region of the transition to the lowest excited singlet (S1) 1B1u state are measured by the fluorescence excitation and the single-vibronic-level dispersed fluorescence methods. Strength is defined as the difference in potential energies between the planar and perpendicular conformations. BPEB possesses two large-amplitude torsional motions, out-of-phase 24 and in-phase 29 modes. The most stable is the planar conformation, and barrier heights at the perpendicular conformation are coincident in torsional potentials for the two modes. Torsional levels are successively observed up to 19± and 16- quantum levels in the ground state, respectively. Strength is determined to be 293 cm-1 (3.51 kJmol-1) with an accuracy of an error range smaller than 1 cm-1. In the excited state, strength is estimated to be 1549 ± 73 cm-1. Combination levels of two torsional modes are also measured up to high quantum levels. A systematic decrease in frequencies is observed with increasing the quantum number. Quantum-chemistry calculations of B3LYP, CAM-B3PLYP, WB97XD, and M062X with basis sets of aug-cc-pVDZ are performed, where B3LYP theories are carried out with the dispersion correlation. The calculated strength is 1.1-2.1 times larger than observed.
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Affiliation(s)
- Ryoko Suzuki
- Departments of Chemical Biology and Applied Chemistry, Graduate School of Engineering, Nihon University, Koriyama, Fukushima 963-8642, Japan
| | - Kohei Chiba
- Departments of Chemical Biology and Applied Chemistry, Graduate School of Engineering, Nihon University, Koriyama, Fukushima 963-8642, Japan
| | - Sei'ichi Tanaka
- Departments of Chemical Biology and Applied Chemistry, Graduate School of Engineering, Nihon University, Koriyama, Fukushima 963-8642, Japan
| | - Katsuhiko Okuyama
- Departments of Chemical Biology and Applied Chemistry, College of Engineering, Nihon University, Koriyama, Fukushima 963-8642, Japan
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4
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Sposini V, Likos CN, Camargo M. Glassy phases of the Gaussian core model. SOFT MATTER 2023. [PMID: 38050434 DOI: 10.1039/d3sm01314f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/06/2023]
Abstract
We present results from molecular dynamics simulations exploring the supercooled dynamics of the Gaussian Core Model in the low- and intermediate-density regimes. In particular, we analyse the transition from the low-density hard-sphere-like glassy dynamics to the high-density one. The dynamics at low densities is well described by the caging mechanism, giving rise to intermittent dynamics. At high densities, the particles undergo a more continuous motion in which the concept of cage loses its meaning. We elaborate on the idea that these different supercooled dynamics are in fact the precursors of two different glass states.
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Affiliation(s)
- Vittoria Sposini
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria.
| | - Christos N Likos
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria.
| | - Manuel Camargo
- Facultad de Ciencias & CICBA, Universidad Antonio Nariño-Campus Farallones, Km 18 via Cali-Jamundí, 760030 Cali, Colombia
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5
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Sorkin B, Diamant H, Ariel G. Universal Relation between Entropy and Kinetics. PHYSICAL REVIEW LETTERS 2023; 131:147101. [PMID: 37862659 DOI: 10.1103/physrevlett.131.147101] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 08/25/2023] [Indexed: 10/22/2023]
Abstract
Relating thermodynamic and kinetic properties is a conceptual challenge with many practical benefits. Here, based on first principles, we derive a rigorous inequality relating the entropy and the dynamic propagator of particle configurations. It is universal and applicable to steady states arbitrarily far from thermodynamic equilibrium. Applying the general relation to diffusive dynamics yields a relation between the entropy and the (normal or anomalous) diffusion coefficient. The relation can be used to obtain useful bounds for the late-time diffusion coefficient from the calculated steady-state entropy or, conversely, to estimate the entropy based on measured diffusion coefficients. We demonstrate the validity and usefulness of the relation through several examples and discuss its broad range of applications, in particular, for systems far from equilibrium.
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Affiliation(s)
- Benjamin Sorkin
- School of Chemistry and Center for Physics and Chemistry of Living Systems, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Haim Diamant
- School of Chemistry and Center for Physics and Chemistry of Living Systems, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Gil Ariel
- Department of Mathematics, Bar-Ilan University, 52000 Ramat Gan, Israel
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6
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Kaśkosz F, Koperwas K, Grzybowski A, Paluch M. The origin of the density scaling exponent for polyatomic molecules and the estimation of its value from the liquid structure. J Chem Phys 2023; 158:144503. [PMID: 37061492 DOI: 10.1063/5.0141975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2023] Open
Abstract
In this article, we unravel the problem of interpreting the density scaling exponent for the polyatomic molecules representing the real van der Waals liquids. Our studies show that the density scaling exponent is a weighted average of the exponents of the repulsive terms of all interatomic interactions that occur between molecules, where the potential energy of a given interaction represents its weight. It implies that potential energy is a key quantity required to calculate the density scaling exponent value for real molecules. Finally, we use the well-known method for potential energy estimation and show that the density scaling exponent could be successfully predicted from the liquid structure for fair representatives of the real systems.
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Affiliation(s)
- F Kaśkosz
- University of Silesia in Katowice, Institute of Physics, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland
| | - K Koperwas
- University of Silesia in Katowice, Institute of Physics, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland
| | - A Grzybowski
- University of Silesia in Katowice, Institute of Physics, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland
| | - M Paluch
- University of Silesia in Katowice, Institute of Physics, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland
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7
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Moradzadeh A, Aluru NR. Understanding simple liquids through statistical and deep learning approaches. J Chem Phys 2021; 154:204503. [PMID: 34241171 DOI: 10.1063/5.0046226] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Statistical and deep learning-based methods are employed to obtain insights into the quasi-universal properties of simple liquids. In the first part, a statistical model is employed to provide a probabilistic explanation for the similarity in the structure of simple liquids interacting with different pair potential forms, collectively known as simple liquids. The methodology works by sampling the radial distribution function and the number of interacting particles within the cutoff distance, and it produces the probability density function of the net force. We show that matching the probability distribution of the net force can be a direct route to parameterize simple liquid pair potentials with a similar structure, as the net force is the main component of the Newtonian equations of motion. The statistical model is assessed and validated against various cases. In the second part, we exploit DeepILST [A. Moradzadeh and N. R. Aluru, J. Phys. Chem. Lett. 10, 1242-1250 (2019)], a data-driven and deep-learning assisted framework to parameterize the standard 12-6 Lennard-Jones (LJ) pair potential, to find structurally equivalent/isomorphic LJ liquids that identify constant order parameter [τ=∫0 ξcf gξ-1ξ2dξ, where gξ and ξ(=rρ13) are the reduced radial distribution function and radial distance, respectively] systems in the space of non-dimensional temperature and density of the LJ liquids. We also investigate the consistency of DeepILST in reproducibility of radial distribution functions of various quasi-universal potentials, e.g., exponential, inverse-power-law, and Yukawa pair potentials, quantified based on the radial distribution functions and Kullback-Leibler errors. Our results provide insights into the quasi-universality of simple liquids using the statistical and deep learning methods.
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Affiliation(s)
- A Moradzadeh
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - N R Aluru
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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8
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Treffenstädt LL, Schmidt M. Universality in Driven and Equilibrium Hard Sphere Liquid Dynamics. PHYSICAL REVIEW LETTERS 2021; 126:058002. [PMID: 33605743 DOI: 10.1103/physrevlett.126.058002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Revised: 12/04/2020] [Accepted: 01/05/2021] [Indexed: 06/12/2023]
Abstract
We demonstrate that the time evolution of the van Hove dynamical pair correlation function is governed by adiabatic forces that arise from the free energy and by superadiabatic forces that are induced by the flow of the van Hove function. The superadiabatic forces consist of drag, viscous, and structural contributions, as occur in active Brownian particles, in liquids under shear and in lane forming mixtures. For hard sphere liquids, we present a power functional theory that predicts these universal force fields in quantitative agreement with our Brownian dynamics simulation results.
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Affiliation(s)
- Lucas L Treffenstädt
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95447 Bayreuth, Germany
| | - Matthias Schmidt
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95447 Bayreuth, Germany
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9
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Scaling of relaxation and excess entropy in plastically deformed amorphous solids. Proc Natl Acad Sci U S A 2020; 117:11887-11893. [PMID: 32430317 DOI: 10.1073/pnas.2000698117] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
When stressed sufficiently, solid materials yield and deform plastically via reorganization of microscopic constituents. Indeed, it is possible to alter the microstructure of materials by judicious application of stress, an empirical process utilized in practice to enhance the mechanical properties of metals. Understanding the interdependence of plastic flow and microscopic structure in these nonequilibrium states, however, remains a major challenge. Here, we experimentally investigate this relationship, between the relaxation dynamics and microscopic structure of disordered colloidal solids during plastic deformation. We apply oscillatory shear to solid colloidal monolayers and study their particle trajectories as a function of shear rate in the plastic regime. Under these circumstances, the strain rate, the relaxation rate associated with plastic flow, and the sample microscopic structure oscillate together, but with different phases. Interestingly, the experiments reveal that the relaxation rate associated with plastic flow at time t is correlated with the strain rate and sample microscopic structure measured at earlier and later times, respectively. The relaxation rate, in this nonstationary condition, exhibits power-law, shear-thinning behavior and scales exponentially with sample excess entropy. Thus, measurement of sample static structure (excess entropy) provides insight about both strain rate and constituent rearrangement dynamics in the sample at earlier times.
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10
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Fischer M, Bauer G, Gross J. Transferable Anisotropic United-Atom Mie (TAMie) Force Field: Transport Properties from Equilibrium Molecular Dynamic Simulations. Ind Eng Chem Res 2020. [DOI: 10.1021/acs.iecr.0c00848] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Matthias Fischer
- Institute of Thermodynamics and Thermal Process Engineering, University of Stuttgart, Pfaffenwaldring 9, 70569 Stuttgart, Germany
| | - Gernot Bauer
- Institute of Thermodynamics and Thermal Process Engineering, University of Stuttgart, Pfaffenwaldring 9, 70569 Stuttgart, Germany
| | - Joachim Gross
- Institute of Thermodynamics and Thermal Process Engineering, University of Stuttgart, Pfaffenwaldring 9, 70569 Stuttgart, Germany
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11
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Liu K, Wang Y, Du Z, Zhang C, Mi J. Anisotropic Dynamics of Binary Particles in Confined Geometries. Chemphyschem 2020; 21:531-539. [DOI: 10.1002/cphc.201901163] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Revised: 02/06/2020] [Indexed: 11/05/2022]
Affiliation(s)
- Kun Liu
- State Key Laboratory of Organic-Inorganic CompositesBeijing University of Chemical Technology Beijing 100029 China
- Changzhou Institute of Advanced MaterialsBeijing University of Chemical Technology Beijing 100029 China
| | - Yue Wang
- State Key Laboratory of Organic-Inorganic CompositesBeijing University of Chemical Technology Beijing 100029 China
| | - Zhongjie Du
- Changzhou Institute of Advanced MaterialsBeijing University of Chemical Technology Beijing 100029 China
| | - Chen Zhang
- Changzhou Institute of Advanced MaterialsBeijing University of Chemical Technology Beijing 100029 China
| | - Jianguo Mi
- State Key Laboratory of Organic-Inorganic CompositesBeijing University of Chemical Technology Beijing 100029 China
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12
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Koperwas K, Grzybowski A, Paluch M. Exploring the connection between the density-scaling exponent and the intermolecular potential for liquids on the basis of computer simulations of quasireal model systems. Phys Rev E 2020; 101:012613. [PMID: 32069552 DOI: 10.1103/physreve.101.012613] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Indexed: 11/07/2022]
Abstract
In this paper, based on the molecular dynamics simulations of quasireal model systems, we propose a method for determination of the effective intermolecular potential for real materials. We show that in contrast to the simple liquids, the effective intermolecular potential for the studied systems depends on the thermodynamic conditions. Nevertheless, the previously established relationship for simple liquids between the exponent of the inverse power law approximation of intermolecular potential and the density-scaling exponent is still preserved when small enough intermolecular distances are considered. However, our studies show that molecules approach each other at these very short distances relatively rarely. Consequently, only sparse interactions between extremely close molecules determine the value of the scaling exponent and then strongly influence the connection between dynamics and thermodynamics of the whole system.
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Affiliation(s)
- K Koperwas
- University of Silesia in Katowice, Institute of Physics, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland and Silesian Center for Education and Interdisciplinary Research (SMCEBI), 75 Pułku Piechoty 1a, 41-500 Chorzów, Poland
| | - A Grzybowski
- University of Silesia in Katowice, Institute of Physics, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland and Silesian Center for Education and Interdisciplinary Research (SMCEBI), 75 Pułku Piechoty 1a, 41-500 Chorzów, Poland
| | - M Paluch
- University of Silesia in Katowice, Institute of Physics, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland and Silesian Center for Education and Interdisciplinary Research (SMCEBI), 75 Pułku Piechoty 1a, 41-500 Chorzów, Poland
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13
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Hopp M, Mele J, Hellmann R, Gross J. Thermal Conductivity via Entropy Scaling: An Approach That Captures the Effect of Intramolecular Degrees of Freedom. Ind Eng Chem Res 2019. [DOI: 10.1021/acs.iecr.9b03998] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Madlen Hopp
- Institute of Thermodynamics and Thermal Process Engineering, University of Stuttgart, 70569 Stuttgart, Germany
| | - Julia Mele
- Institute of Thermodynamics and Thermal Process Engineering, University of Stuttgart, 70569 Stuttgart, Germany
| | - Robert Hellmann
- Institute of Chemistry, University of Rostock, 18055 Rostock, Germany
| | - Joachim Gross
- Institute of Thermodynamics and Thermal Process Engineering, University of Stuttgart, 70569 Stuttgart, Germany
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14
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Bell IH, Messerly R, Thol M, Costigliola L, Dyre JC. Modified Entropy Scaling of the Transport Properties of the Lennard-Jones Fluid. J Phys Chem B 2019; 123:6345-6363. [PMID: 31241958 DOI: 10.1021/acs.jpcb.9b05808] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Rosenfeld proposed two different scaling approaches to model the transport properties of fluids, separated by 22 years, one valid in the dilute gas, and another in the liquid phase. In this work, we demonstrate that these two limiting cases can be connected through the use of a novel approach to scaling transport properties and a bridging function. This approach, which is empirical and not derived from theory, is used to generate reference correlations for the transport properties of the Lennard-Jones 12-6 fluid of viscosity, thermal conductivity, and self-diffusion. This approach, with a very simple functional form, allows for the reproduction of the most accurate simulation data to within nearly their statistical uncertainty. The correlations are used to confirm that for the Lennard-Jones fluid the appropriately scaled transport properties are nearly monovariate functions of the excess entropy from low-density gases into the supercooled phase and up to extreme temperatures. This study represents the most comprehensive metastudy of the transport properties of the Lennard-Jones fluid to date.
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Affiliation(s)
- Ian H Bell
- Applied Chemicals and Materials Division , National Institute of Standards and Technology , Boulder , Colorado 80305 , United States
| | - Richard Messerly
- Applied Chemicals and Materials Division , National Institute of Standards and Technology , Boulder , Colorado 80305 , United States
| | - Monika Thol
- Thermodynamics , Ruhr-Universität Bochum , Universitätsstraße 150 , 44801 Bochum , Germany
| | - Lorenzo Costigliola
- DNRF Centre "Glass and Time," IMFUFA, Department of Science and Environment , Roskilde University , Postbox 260, DK-4000 Roskilde , Denmark
| | - Jeppe C Dyre
- DNRF Centre "Glass and Time," IMFUFA, Department of Science and Environment , Roskilde University , Postbox 260, DK-4000 Roskilde , Denmark
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15
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Ma X, Liu J, Zhang Y, Habdas P, Yodh AG. Excess entropy and long-time diffusion in colloidal fluids with short-range interparticle attraction. J Chem Phys 2019; 150:144907. [PMID: 30981231 DOI: 10.1063/1.5091564] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Liquid structure and dynamics are experimentally investigated in colloidal suspensions with short-range depletion attraction. The colloidal fluid samples consist of hard-sphere colloidal particles suspended along with rodlike depletants based on surfactant micelles. The spheres have a range of surface chemistries, diameters, and packing fractions, and the rodlike micelle length depends on the temperature. Thus, the combination of hard-spheres and depletants generates a sample wherein short-range interparticle attraction can be temperature-tuned in situ. Video optical microscopy and particle tracking techniques are employed to measure particle trajectories from which structural and dynamical quantities are derived, including the particle pair correlation function [g(r)], mean square displacement, long-time diffusion coefficient, and the sample two-body excess entropy (S2). The samples with stronger short-range attractions exhibit more order, as characterized by g(r) and S2. The stronger short-range attractions are also observed to lead to slower long-time diffusion and more heterogeneous dynamics at intermediate time scales. Finally, the excess entropy scaling law prediction, i.e., the exponential relationship between two-body excess entropy and long-time diffusivity, is observed across the full range of samples.
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Affiliation(s)
- Xiaoguang Ma
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Jiachen Liu
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Yikang Zhang
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Piotr Habdas
- Department of Physics, Saint Joseph's University, Philadelphia, Pennsylvania 19131, USA
| | - A G Yodh
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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16
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Koperwas K, Grzybowski A, Paluch M. The effect of molecular architecture on the physical properties of supercooled liquids studied by MD simulations: Density scaling and its relation to the equation of state. J Chem Phys 2019; 150:014501. [PMID: 30621418 DOI: 10.1063/1.5050330] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Theoretical concepts in condensed matter physics are typically verified and also developed by exploiting computer simulations mostly in simple models. Predictions based on these usually isotropic models are often at odds with measurement results obtained for real materials. One of the examples is an intriguing problem within the density scaling idea that has attracted attention in recent decades due to its hallmarks of universality, i.e., the fact that the difference between the density scaling exponent and the exponent of the equation of state is observed for real materials, whereas it has not been reported for the model system. In this paper, we use new model molecules of simple but anisotropic architecture to study the effect of molecular anisotropy on the dynamic and thermodynamic properties of the system. We identify the applicable range of intermolecular interactions for a given physical process, and then we explain the reason for observed differences between the behavior of the model and real systems. It demonstrates that the new model systems open broad perspectives for simulation and theoretical research, for example, into unifying concepts in the glass transition physics.
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Affiliation(s)
- K Koperwas
- Institute of Physics, University of Silesia in Katowice, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland
| | - A Grzybowski
- Institute of Physics, University of Silesia in Katowice, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland
| | - M Paluch
- Institute of Physics, University of Silesia in Katowice, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland
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17
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Abstract
This article gives an overview of excess-entropy scaling, the 1977 discovery by Rosenfeld that entropy determines properties of liquids like viscosity, diffusion constant, and heat conductivity. We give examples from computer simulations confirming this intriguing connection between dynamics and thermodynamics, counterexamples, and experimental validations. Recent uses in application-related contexts are reviewed, and theories proposed for the origin of excess-entropy scaling are briefly summarized. It is shown that if two thermodynamic state points of a liquid have the same microscopic dynamics, they must have the same excess entropy. In this case, the potential-energy function exhibits a symmetry termed hidden scale invariance, stating that the ordering of the potential energies of configurations is maintained if these are scaled uniformly to a different density. This property leads to the isomorph theory, which provides a general framework for excess-entropy scaling and illuminates, in particular, why this does not apply rigorously and universally. It remains an open question whether all aspects of excess-entropy scaling and related regularities reflect hidden scale invariance in one form or other.
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Affiliation(s)
- Jeppe C Dyre
- Glass and Time, IMFUFA, Department of Science and Environment, Roskilde University, P.O. Box 260, DK-4000 Roskilde, Denmark
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18
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Hopp M, Mele J, Gross J. Self-Diffusion Coefficients from Entropy Scaling Using the PCP-SAFT Equation of State. Ind Eng Chem Res 2018. [DOI: 10.1021/acs.iecr.8b02406] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Madlen Hopp
- Institute of Thermodynamics and Thermal Process Engineering, University of Stuttgart, 70569 Stuttgart, Germany
| | - Julia Mele
- Institute of Thermodynamics and Thermal Process Engineering, University of Stuttgart, 70569 Stuttgart, Germany
| | - Joachim Gross
- Institute of Thermodynamics and Thermal Process Engineering, University of Stuttgart, 70569 Stuttgart, Germany
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19
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Desgranges C, Delhommelle J. Non-monotonic variations of the nucleation free energy in a glass-forming ultra-soft particles fluid. SOFT MATTER 2018; 14:5977-5985. [PMID: 29911716 DOI: 10.1039/c8sm00887f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Using molecular dynamics simulation, we study the impact of the degree of supercooling on the crystal nucleation of ultra-soft particles, modeled with the Gaussian core potential. Focusing on systems with a high number density, our simulations reveal dramatically different behaviors as the degree of supercooling is varied. In the moderate supercooling regime, crystal nucleation proceeds as expected from classical nucleation theory, with a decrease in the free energy of nucleation, as well as in the size of the critical nucleus, as supercooling is increased. On the other hand, in the large supercooling regime, we observe an unusual reversal of behavior with an increase in the free energy of nucleation and in the critical size, as supercooling is increased. This unexpected result is analyzed in terms of the interplay between the glass transition and the crystal nucleation process. Specifically, medium range order crystal-like domains, with structural features different from that of the crystal nucleus, are found to form throughout the system when the supercooling is very large. These, in turn, play a pivotal role in the increase in the free energy of nucleation, as well as in the critical size, as the temperature gets closer to the glass transition.
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Affiliation(s)
- Caroline Desgranges
- Department of Chemistry, University of North Dakota, Grand Forks, ND 58202, USA.
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20
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Olsen AE, Dyre JC, Schrøder TB. Communication: Pseudoisomorphs in liquids with intramolecular degrees of freedom. J Chem Phys 2016; 145:241103. [DOI: 10.1063/1.4972860] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Andreas Elmerdahl Olsen
- Glass and Time, IMFUFA, Department of Science and Environment, Roskilde University, P.O. Box 260, DK-4000 Roskilde, Denmark
| | - Jeppe C. Dyre
- Glass and Time, IMFUFA, Department of Science and Environment, Roskilde University, P.O. Box 260, DK-4000 Roskilde, Denmark
| | - Thomas B. Schrøder
- Glass and Time, IMFUFA, Department of Science and Environment, Roskilde University, P.O. Box 260, DK-4000 Roskilde, Denmark
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21
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Herrera-Velarde S, Pérez-Angel G, Castañeda-Priego R. One-dimensional Gaussian-core fluid: ordering and crossover from normal diffusion to single-file dynamics. SOFT MATTER 2016; 12:9047-9057. [PMID: 27774539 DOI: 10.1039/c6sm01558a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The peculiarity of a bounded pair potential in combination with strong confinement brings some quite interesting new phenomenology in the structure and dynamics of one-dimensional colloidal systems. Such behaviour is atypical in comparison with colloidal systems interacting with potentials that diverge at the origin. In this contribution, by means of molecular dynamics simulations, a confined one-dimensional model of particles interacting via a Gaussian-core pair potential is studied. We explore the effects of confinement, density and temperature on the structural and dynamical correlation functions. Our findings indicate that the static and dynamic liquid-state anomalies already reported in open systems are also present in this 1D model system. Using the radial distribution function and the static structure factor to characterise the spatial ordering, it is observed that the system remains fluid at all densities. However, when the reduced temperature is above 0.03, it displays typical features of a liquid regime, i.e., there exist short-range spatial correlations among particles. In contrast, at lower temperatures and densities, where the particle-particle interaction dominates, the system behaves structurally and dynamically similar to a hard-core repulsive system. In such a region, interestingly, there is a crossover from a liquid to a solid-like regime. At any given temperature, the system undergoes a sort of reentrant structural behaviour as the density increases. At either high densities or temperatures, particle correlations vanish, thus, the system exhibits structural and dynamical properties similar to those of an ideal gas. To examine a possible correlation between the structural anomalies and the diffusive behaviour, the mean-square displacement and the self-intermediate scattering function are also computed. From these observables, we establish the thermodynamic phase-space points where the dynamical behaviour is non-monotonic. In conjunction with the observed anomalous diffusion, we have found a dynamical crossover from single-file diffusion, which is characteristic of one-dimensional systems with a well-defined hard-core, to the ordinary Fickian diffusion present in open systems.
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Affiliation(s)
- Salvador Herrera-Velarde
- Subdirección de Postgrado e Investigación, Instituto Tecnológico Superior de Xalapa, Sección 5A Reserva Territorial s/n, 91096, Xalapa, Veracruz, Mexico
| | - Gabriel Pérez-Angel
- Departamento de Física Aplicada, Cinvestav, Unidad Mérida, Apartado Postal 73 Cordemex, 97310, Mérida, Yucatán, Mexico
| | - Ramón Castañeda-Priego
- División de Ciencias e Ingenierías, Campus León, Universidad de Guanajuato, Loma del Bosque 103, Lomas del Campestre, 37150 León, Guanajuato, Mexico.
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22
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Jadrich RB, Lindquist BA, Bollinger JA, Truskett TM. Consequences of minimising pair correlations in fluids for dynamics, thermodynamics and structure. Mol Phys 2016. [DOI: 10.1080/00268976.2016.1159742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- R. B. Jadrich
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, USA
| | - B. A. Lindquist
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, USA
| | - J. A. Bollinger
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, USA
| | - T. M. Truskett
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, USA
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23
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Bollinger JA, Jain A, Truskett TM. How Local and Average Particle Diffusivities of Inhomogeneous Fluids Depend on Microscopic Dynamics. J Phys Chem B 2015; 119:9103-13. [PMID: 25350488 DOI: 10.1021/jp508887r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Computer simulations and a stochastic Fokker-Planck equation based approach are used to compare the single-particle diffusion coefficients of equilibrium hard-sphere fluids exhibiting identical inhomogeneous static structure and governed by either Brownian (i.e., overdamped Langevin) or Newtonian microscopic dynamics. The physics of inhomogeneity is explored via the imposition of one-dimensional sinusoidal density profiles of different wavelengths and amplitudes. When imposed density variations are small in magnitude for distances on the scale of a particle diameter, bulk-like average correlations between local structure and mobility are observed. In contrast, when density variations are significant on that length scale, qualitatively different structure-mobility correlations emerge that are sensitive to the governing microscopic dynamics. Correspondingly, a previously proposed scaling between long-time diffusivities for bulk isotropic fluids of particles exhibiting Brownian versus Newtonian dynamics [Pond et al. Soft Matter 2011, 7, 9859-9862] cannot be generalized to describe the position-dependent behaviors of strongly inhomogeneous fluids. While average diffusivities in the inhomogeneous and homogeneous directions are coupled, their qualitative dependencies on inhomogeneity wavelength are sensitive to the details of the microscopic dynamics. Nonetheless, average diffusivities of the inhomogeneous fluids can be approximately predicted for either type of dynamics based on knowledge of bulk isotropic fluid behavior and how inhomogeneity modifies the distribution of available volume. Analogous predictions for average diffusivities of experimental, inhomogeneous colloidal dispersions (based on known bulk behavior) suggest that they will exhibit qualitatively different trends than those predicted by models governed by overdamped Langevin dynamics that do not account for hydrodynamic interactions.
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Affiliation(s)
- Jonathan A Bollinger
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, United States
| | - Avni Jain
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, United States
| | - Thomas M Truskett
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, United States
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24
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Schrøder TB, Dyre JC. Simplicity of condensed matter at its core: generic definition of a Roskilde-simple system. J Chem Phys 2015; 141:204502. [PMID: 25429949 DOI: 10.1063/1.4901215] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The isomorph theory is reformulated by defining Roskilde-simple systems by the property that the order of the potential energies of configurations at one density is maintained when these are scaled uniformly to a different density. If the potential energy as a function of all particle coordinates is denoted by U(R), this requirement translates into U(Ra) < U(Rb) ⇒ U(λRa) < U(λRb). Isomorphs remain curves in the thermodynamic phase diagram along which structure, dynamics, and excess entropy are invariant, implying that the phase diagram is effectively one-dimensional with respect to many reduced-unit properties. In contrast to the original formulation of the isomorph theory, however, the density-scaling exponent is not exclusively a function of density and the isochoric heat capacity is not an exact isomorph invariant. A prediction is given for the latter quantity's variation along the isomorphs. Molecular dynamics simulations of the Lennard-Jones and Lennard-Jones Gaussian systems validate the new approach.
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Affiliation(s)
- Thomas B Schrøder
- DNRF Centre "Glass and Time," IMFUFA, Department of Sciences, Roskilde University, Postbox 260, DK-4000 Roskilde, Denmark
| | - Jeppe C Dyre
- DNRF Centre "Glass and Time," IMFUFA, Department of Sciences, Roskilde University, Postbox 260, DK-4000 Roskilde, Denmark
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25
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Grzybowska K, Grzybowski A, Pawlus S, Pionteck J, Paluch M. Role of entropy in the thermodynamic evolution of the time scale of molecular dynamics near the glass transition. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:062305. [PMID: 26172717 DOI: 10.1103/physreve.91.062305] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Indexed: 06/04/2023]
Abstract
In this paper, we investigate how changes in the system entropy influence the characteristic time scale of the system molecular dynamics near the glass transition. Independently of any model of thermodynamic evolution of the time scale, against some previous suppositions, we show that the system entropy S is not sufficient to govern the time scale defined by structural relaxation time τ. In the density scaling regime, we argue that the decoupling between τ and S is a consequence of different values of the scaling exponents γ and γ(S) in the density scaling laws, τ=f(ρ(γ)/T) and S=h(ρ(γ(S))/T), where ρ and T denote density and temperature, respectively. It implies that the proper relation between τ and S requires supplementing with a density factor, u(ρ), i.e., τ=g(u(ρ)w(S)). This meaningful finding additionally demonstrates that the density scaling idea can be successfully used to separate physically relevant contributions to the time scale of molecular dynamics near the glass transition. The relation reported by us between τ and S constitutes a general pattern based on nonconfigurational quantities for describing the thermodynamic evolution of the characteristic time scale of molecular dynamics near the glass transition in the density scaling regime, which is a promising alternative to the approaches based as the Adam-Gibbs model on the configurational entropy that is difficult to evaluate in the entire thermodynamic space. As an example, we revise the Avramov entropic model of the dependence τ(T,ρ), giving evidence that its entropic basis has to be extended by the density dependence of the maximal energy barrier for structural relaxation. We also discuss the excess entropy S(ex), the density scaling of which is found to mimic the density scaling of the total system entropy S.
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Affiliation(s)
- K Grzybowska
- Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice, Poland
- Silesian Center for Education and Interdisciplinary Research, 75 Pułku Piechoty 1A, 41-500 Chorzów, Poland
| | - A Grzybowski
- Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice, Poland
- Silesian Center for Education and Interdisciplinary Research, 75 Pułku Piechoty 1A, 41-500 Chorzów, Poland
| | - S Pawlus
- Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice, Poland
- Silesian Center for Education and Interdisciplinary Research, 75 Pułku Piechoty 1A, 41-500 Chorzów, Poland
| | - J Pionteck
- Leibniz Institute of Polymer Research Dresden, Hohe Strasse 6, D-01069 Dresden, Germany
| | - M Paluch
- Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice, Poland
- Silesian Center for Education and Interdisciplinary Research, 75 Pułku Piechoty 1A, 41-500 Chorzów, Poland
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26
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Bollinger JA, Jain A, Carmer J, Truskett TM. Communication: Local structure-mobility relationships of confined fluids reverse upon supercooling. J Chem Phys 2015; 142:161102. [DOI: 10.1063/1.4919688] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Jonathan A. Bollinger
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA
| | - Avni Jain
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA
| | - James Carmer
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA
| | - Thomas M. Truskett
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA
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27
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Hollingshead KB, Truskett TM. Predicting the structure of fluids with piecewise constant interactions: Comparing the accuracy of five efficient integral equation theories. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:043307. [PMID: 25974612 DOI: 10.1103/physreve.91.043307] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Indexed: 06/04/2023]
Abstract
We use molecular dynamics simulations to test integral equation theory predictions for the structure of fluids of spherical particles with eight different piecewise-constant pair-interaction forms comprising a hard core and a combination of two shoulders and/or wells. Since model pair potentials like these are of interest for discretized or coarse-grained representations of effective interactions in complex fluids (e.g., for computationally intensive inverse optimization problems), we focus here on assessing how accurately their properties can be predicted by analytical or simple numerical closures including Percus-Yevick, hypernetted-chain, and reference hypernetted-chain closures and first-order mean spherical and modified first-order mean spherical approximations. To make quantitative comparisons between the predicted and simulated radial distribution functions, we introduce a cumulative structural error metric. For equilibrium fluid state points of these models, we find that the reference hypernetted-chain closure is the most accurate of the tested approximations as characterized by this metric or related thermodynamic quantities.
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Affiliation(s)
- Kyle B Hollingshead
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA
| | - Thomas M Truskett
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA
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28
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Carmer J, Jain A, Bollinger JA, van Swol F, Truskett TM. Tuning structure and mobility of solvation shells surrounding tracer additives. J Chem Phys 2015; 142:124501. [PMID: 25833590 DOI: 10.1063/1.4916053] [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
Molecular dynamics simulations and a stochastic Fokker-Planck equation based approach are used to illuminate how position-dependent solvent mobility near one or more tracer particle(s) is affected when tracer-solvent interactions are rationally modified to affect corresponding solvation structure. For tracers in a dense hard-sphere fluid, we compare two types of tracer-solvent interactions: (1) a hard-sphere-like interaction, and (2) a soft repulsion extending beyond the hard core designed via statistical mechanical theory to enhance tracer mobility at infinite dilution by suppressing coordination-shell structure [Carmer et al., Soft Matter 8, 4083-4089 (2012)]. For the latter case, we show that the mobility of surrounding solvent particles is also increased by addition of the soft repulsive interaction, which helps to rationalize the mechanism underlying the tracer's enhanced diffusivity. However, if multiple tracer surfaces are in closer proximity (as at higher tracer concentrations), similar interactions that disrupt local solvation structure instead suppress the position-dependent solvent dynamics.
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Affiliation(s)
- James Carmer
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA
| | - Avni Jain
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA
| | - Jonathan A Bollinger
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA
| | - Frank van Swol
- Sandia National Laboratories, Department 1814, P.O. Box 5800, Albuquerque, New Mexico 87185, USA
| | - Thomas M Truskett
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA
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29
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Ranka M, Varkey N, Ramakrishnan S, Zukoski CF. Impact of small changes in particle surface chemistry for unentangled polymer nanocomposites. SOFT MATTER 2015; 11:1634-1645. [PMID: 25600762 DOI: 10.1039/c4sm01598c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report microstructural and rheological consequences of altering silica particle surface chemistry when the particles are suspended in unentangled polyethylene glycol with a molecular weight of 400. The particle surfaces are altered by reacting them with isobutyltrimethyoxysilane. Levels of silanization are chosen so that the particles remain dispersed in the polymer at all volume fractions studied. Our studies indicate that at the levels studied, silanization does not alter the hydrodynamic thickness of the absorbed polymer layer thickness. Rheological properties are not sensitive to levels of silanization up to particle volume fractions where the average particle separation h ∼ 6Rg (4.8 nm). At these volume fractions, composite microstructure undergoes changes associated with jamming of soft particles (decorrelations in the first peak of the particle structure factor and the onset of a non-diffusive mechanism that dominates particle density fluctuations at short times.) In the region of volume fractions where h/Rg < 6, the zero-shear rate viscosity of the composites is extremely sensitive to level of silanization with a decrease in the zero-shear rate viscosity by four orders of magnitude observed for the highest levels of silanization studied in comparison to the bare particles.
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Affiliation(s)
- Moulik Ranka
- University of Illinois, Urbana-Champaign - Department of Chemical and Biomolecular Engineering, Urbana, Illinois, USA
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30
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Ouyang W, Sun B, Sun Z, Xu S. Structural and dynamical anomalies of soft particles interacting through harmonic repulsions. Phys Chem Chem Phys 2015; 17:5734-42. [DOI: 10.1039/c4cp05402d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Molecular dynamics (MD) simulations are carried out to investigate the structural and dynamical anomalies in the core-softened fluid with harmonic repulsions.
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Affiliation(s)
- Wenze Ouyang
- Key Laboratory of Microgravity (National Microgravity Laboratory)
- Institute of Mechanics
- Chinese Academy of Sciences
- Beijing 100190
- People's Republic of China
| | - Bin Sun
- School of Materials and Chemical Engineering
- Zhongyuan University of Technology
- Zhengzhou 450007
- People's Republic of China
| | - Zhiwei Sun
- Key Laboratory of Microgravity (National Microgravity Laboratory)
- Institute of Mechanics
- Chinese Academy of Sciences
- Beijing 100190
- People's Republic of China
| | - Shenghua Xu
- Key Laboratory of Microgravity (National Microgravity Laboratory)
- Institute of Mechanics
- Chinese Academy of Sciences
- Beijing 100190
- People's Republic of China
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31
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Bacher AK, Schrøder TB, Dyre JC. Explaining why simple liquids are quasi-universal. Nat Commun 2014; 5:5424. [DOI: 10.1038/ncomms6424] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 09/30/2014] [Indexed: 11/09/2022] Open
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32
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Bomont JM, Bretonnet JL. Thermodynamics and dynamics of the hard-sphere system: From stable to metastable states. Chem Phys 2014. [DOI: 10.1016/j.chemphys.2014.05.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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33
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Abstract
Recent developments show that many liquids and solids have an approximate "hidden" scale invariance that implies the existence of lines in the thermodynamic phase diagram, so-called isomorphs, along which structure and dynamics in properly reduced units are invariant to a good approximation. This means that the phase diagram becomes effectively one-dimensional with regard to several physical properties. Liquids and solids with isomorphs include most or all van der Waals bonded systems and metals, as well as weakly ionic or dipolar systems. On the other hand, systems with directional bonding (hydrogen bonds or covalent bonds) or strong Coulomb forces generally do not exhibit hidden scale invariance. The article reviews the theory behind this picture of condensed matter and the evidence for it coming from computer simulations and experiments.
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Affiliation(s)
- Jeppe C Dyre
- DNRF Center "Glass and Time", IMFUFA, Department of Sciences, Roskilde University , P.O. Box 260, DK-4000 Roskilde, Denmark
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34
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Dyre JC. Isomorphs, hidden scale invariance, and quasiuniversality. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:042139. [PMID: 24229147 DOI: 10.1103/physreve.88.042139] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 08/16/2013] [Indexed: 06/02/2023]
Abstract
This paper first establishes an approximate scaling property of the potential-energy function of a classical liquid with good isomorphs (a Roskilde-simple liquid). This "pseudohomogeneous" property makes explicit that-and in which sense-such a system has a hidden scale invariance. The second part of the paper gives a potential-energy formulation of the quasiuniversality of monatomic Roskilde-simple liquids, which was recently rationalized in terms of the existence of a quasiuniversal single-parameter family of reduced-coordinate constant-potential-energy hypersurfaces [J. C. Dyre, Phys. Rev. E 87, 022106 (2013)]. The new formulation involves a quasiuniversal reduced-coordinate potential-energy function. A few consequences of this are discussed.
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Affiliation(s)
- Jeppe C Dyre
- DNRF Center "Glass and Time,"IMFUFA, Dept. of Sciences, Roskilde University, P. O. Box 260, DK-4000 Roskilde, Denmark
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35
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López-Flores L, Ruíz-Estrada H, Chávez-Páez M, Medina-Noyola M. Dynamic equivalences in the hard-sphere dynamic universality class. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:042301. [PMID: 24229166 DOI: 10.1103/physreve.88.042301] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Indexed: 06/02/2023]
Abstract
We perform systematic simulation experiments on model systems with soft-sphere repulsive interactions to test the predicted dynamic equivalence between soft-sphere liquids with similar static structure. For this we compare the simulated dynamics (mean squared displacement, intermediate scattering function, α-relaxation time, etc.) of different soft-sphere systems, between them and with the hard-sphere liquid. We then show that the referred dynamic equivalence does not depend on the (Newtonian or Brownian) nature of the microscopic laws of motion of the constituent particles, and hence, applies independently to colloidal and to atomic simple liquids. Finally, we verify another more recently proposed dynamic equivalence, this time between the long-time dynamics of an atomic liquid and its corresponding Brownian fluid (i.e., the Brownian system with the same interaction potential).
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Affiliation(s)
- Leticia López-Flores
- Facultad de Ciencias Físico-Matemáticas, Benemérita Universidad Autónoma de Puebla, Apartado Postal 1152, 72000 Puebla, PUE., México
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36
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Srivastava S, Archer LA, Narayanan S. Structure and transport anomalies in soft colloids. PHYSICAL REVIEW LETTERS 2013; 110:148302. [PMID: 25167044 DOI: 10.1103/physrevlett.110.148302] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2012] [Indexed: 06/03/2023]
Abstract
Anomalous trends in nanoparticle correlation and motion are reported in soft nanoparticle suspensions using static and dynamic x-ray scattering measurements. Contrary to normal expectations, we find that particle-particle correlations decrease and particle dynamics become faster as volume fraction rises above a critical particle loading associated with overlap. Our observations bear many similarities to the cascade of structural and transport anomalies reported for complex, network forming molecular fluids such as water, and are argued to share similar physical origins.
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Affiliation(s)
- Samanvaya Srivastava
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, USA
| | - Lynden A Archer
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, USA
| | - Suresh Narayanan
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
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37
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Dyre JC. NVU perspective on simple liquids' quasiuniversality. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 87:022106. [PMID: 23496459 DOI: 10.1103/physreve.87.022106] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Indexed: 06/01/2023]
Abstract
The last half-century of research into the structure, dynamics, and thermodynamics of simple liquids has revealed a number of approximate universalities. This paper argues that simple liquids' reduced-coordinate constant-potential-energy hypersurfaces constitute a quasiuniversal family of compact Riemannian manifolds parametrized by a single number; from this follows the quasiuniversalities.
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Affiliation(s)
- Jeppe C Dyre
- DNRF Centre Glass and Time, IMFUFA, Department of Sciences, Roskilde University, Postbox 260, DK-4000 Roskilde, Denmark.
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38
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Shell MS. Systematic coarse-graining of potential energy landscapes and dynamics in liquids. J Chem Phys 2013; 137:084503. [PMID: 22938246 DOI: 10.1063/1.4746391] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Recent efforts have shown that the dynamic properties of a wide class of liquids can be mapped onto semi-universal scaling laws and constitutive relations that are motivated by thermodynamic analyses of much simpler models. In particular, it has been found that many systems exhibit dynamics whose behavior in state space closely follows that of soft-sphere particles interacting through an inverse power repulsion. In the present work, we show that a recently developed coarse-graining theory provides a natural way to understand how arbitrary liquids can be mapped onto effective soft-sphere models and hence how one might potentially be able to extract underlying dynamical scaling laws. The theory is based on the relative entropy, an information metric that quantifies how well a soft-sphere approximation to a liquid's multidimensional potential energy landscape performs. We show that optimization of the relative entropy not only enables one to extract effective soft-sphere potentials that suggest an inherent scaling of thermodynamic and dynamic properties in temperature-density space, but that also has rather interesting connections to excess entropy based theories of liquid dynamics. We apply the approach to a binary mixture of Lennard-Jones particles, and show that it gives effective soft-sphere scaling laws that well-describe the behavior of the diffusion constants. Our results suggest that the relative entropy formalism may be useful for "perturbative" type theories of dynamics, offering a general strategy for systematically connecting complex energy landscapes to simpler reference ones with better understood dynamic behavior.
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Affiliation(s)
- M Scott Shell
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California 93106-5080, USA.
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Armstrong JA, Chakravarty C, Ballone P. Statistical mechanics of coarse graining: Estimating dynamical speedups from excess entropies. J Chem Phys 2012; 136:124503. [DOI: 10.1063/1.3697383] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Goyal S, Escobedo FA. Structure and transport properties of polymer grafted nanoparticles. J Chem Phys 2011; 135:184902. [DOI: 10.1063/1.3657831] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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Shi Z, Debenedetti PG, Stillinger FH, Ginart P. Structure, dynamics, and thermodynamics of a family of potentials with tunable softness. J Chem Phys 2011; 135:084513. [DOI: 10.1063/1.3627148] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Ikeda A, Miyazaki K. Slow dynamics of the high density Gaussian core model. J Chem Phys 2011; 135:054901. [DOI: 10.1063/1.3615949] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Ikeda A, Miyazaki K. Thermodynamic and structural properties of the high density Gaussian core model. J Chem Phys 2011; 135:024901. [DOI: 10.1063/1.3609277] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
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