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Zhuravlyov V, Goree J, Douglas JF, Elvati P, Violi A. Comparison of the static structure factor at long wavelengths for a dusty plasma liquid and other liquids. Phys Rev E 2022; 106:055212. [PMID: 36559416 DOI: 10.1103/physreve.106.055212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Accepted: 10/23/2022] [Indexed: 06/17/2023]
Abstract
Especially small values of the static structure factor S(k) at long wavelengths, i.e., small k, were obtained in an analysis of experimental data, for a two-dimensional dusty plasma in its liquid state. For comparison, an analysis of S(k) data was carried out for many previously published experiments with other liquids. The latter analysis indicates that the magnitude of S(k) at small k is typically in a range 0.02-0.13. In contrast, the corresponding value for a dusty plasma liquid was found to be as small as 0.0139. Another basic finding for the dusty plasma liquid is that S(k) at small k generally increases with temperature, with its lowest value, noted above, occurring near the melting point. Simulations were carried out for the dusty plasma liquid, and their results are generally consistent with the experiment. Since a dusty plasma has a soft interparticle interaction, our findings support earlier theoretical suggestions that a useful design strategy for creating materials having exceptionally low values of S(0), so-called hyperuniform materials, is the use of a condensed material composed of particles that interact softly at their periphery.
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Affiliation(s)
- Vitaliy Zhuravlyov
- Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242, USA
| | - J Goree
- Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242, USA
| | - Jack F Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Paolo Elvati
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Angela Violi
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
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2
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Bacca M. Mechanics of diffusion-mediated budding and implications for virus replication and infection. J R Soc Interface 2022; 19:20220525. [PMID: 36321373 PMCID: PMC9627455 DOI: 10.1098/rsif.2022.0525] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 10/14/2022] [Indexed: 03/06/2023] Open
Abstract
Budding allows virus replication and macromolecular secretion in cells through the formation of a membrane protrusion (bud) that evolves into an envelope. The largest energetic barrier to bud formation is membrane deflection and is trespassed primarily thanks to nucleocapsid-membrane adhesion. Transmembrane proteins (TPs), which later form the virus ligands, are the main promotors of adhesion and can accommodate membrane bending thanks to an induced spontaneous curvature. Adhesive TPs must diffuse across the membrane from remote regions to gather on the bud surface, thus, diffusivity controls the kinetics. This paper proposes a simple model to describe diffusion-mediated budding unravelling important size limitations and size-dependent kinetics. The predicted optimal virion radius, giving the fastest budding, is validated against experiments for coronavirus, HIV, flu and hepatitis. Assuming exponential replication of virions and hereditary size, the model can predict the size distribution of a virus population. This is verified against experiments for SARS-CoV-2. All the above comparisons rely on the premise that budding poses the tightest size constraint. This is true in most cases, as demonstrated in this paper, where the proposed model is extended to describe virus infection via receptor- and clathrin-mediated endocytosis, and via membrane fusion.
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Affiliation(s)
- Mattia Bacca
- Mechanical Engineering Department, School of Biomedical Engineering, Institute of Applied Mathematics, University of British Columbia, Vancouver, BC Canada V6T1Z4
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3
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Negro G, Caporusso CB, Digregorio P, Gonnella G, Lamura A, Suma A. Hydrodynamic effects on the liquid-hexatic transition of active colloids. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2022; 45:75. [PMID: 36098879 PMCID: PMC9470657 DOI: 10.1140/epje/s10189-022-00230-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 08/25/2022] [Indexed: 05/06/2023]
Abstract
We study numerically the role of hydrodynamics in the liquid-hexatic transition of active colloids at intermediate activity, where motility induced phase separation (MIPS) does not occur. We show that in the case of active Brownian particles (ABP), the critical density of the transition decreases upon increasing the particle's mass, enhancing ordering, while self-propulsion has the opposite effect in the activity regime considered. Active hydrodynamic particles (AHP), instead, undergo the liquid-hexatic transition at higher values of packing fraction [Formula: see text] than the corresponding ABP, suggesting that hydrodynamics have the net effect of disordering the system. At increasing densities, close to the hexatic-liquid transition, we found in the case of AHP the appearance of self-sustained organized motion with clusters of particles moving coherently.
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Affiliation(s)
- G Negro
- Dipartimento di Fisica, Università degli Studi di Bari and INFN, Sezione di Bari, via Amendola 173, Bari, 70126, Italy
| | - C B Caporusso
- Dipartimento di Fisica, Università degli Studi di Bari and INFN, Sezione di Bari, via Amendola 173, Bari, 70126, Italy.
| | - P Digregorio
- Centre Européen de Calcul Atomique et Moléculaire (CECAM), Ecole Polytechnique Fédérale de Lausanne (EPFL), Batochimie, Avenue Forel 2, 1015, Lausanne, Switzerland
| | - G Gonnella
- Dipartimento di Fisica, Università degli Studi di Bari and INFN, Sezione di Bari, via Amendola 173, Bari, 70126, Italy
| | - A Lamura
- Istituto Applicazioni Calcolo, CNR, Via Amendola 122/D, 70126, Bari, Italy
| | - A Suma
- Dipartimento di Fisica, Università degli Studi di Bari and INFN, Sezione di Bari, via Amendola 173, Bari, 70126, Italy
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4
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Wei T, Cao X, Ma D, Li Y, Jia C. Microscopic kinetic theory of the mean collision force of a particle moving in rarefied gases. Phys Rev E 2022; 106:034101. [PMID: 36266785 DOI: 10.1103/physreve.106.034101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 08/15/2022] [Indexed: 06/16/2023]
Abstract
The friction of an incident particle interacting with the background molecules is a cornerstone in the nonequilibrium dynamics and statistics. It is reported that the Stokes force may fail while the Brown particle's size is small enough. In this work, the mean collision force of a small classical particle moving through the rarefied gases is analyzed by the direct calculation of the mean decrease of particle's velocity by elastic collisions. As an example, a whole velocity space applicable mean collision force in Maxwell gas is obtained. A self-consistent solution is further provided based on the numerical simulations. Within the low speed limit, comparison of the friction and the Stokes force has been demonstrated. Although the two forces are both proportional to the speed of the particle, their coefficients are different. Unlike the linear speed dependence of Stokes force, the linear behavior in rarefied gases is broken with increasing the speed of incident particle, and a quadratic speed dependence is resulted in high speed. This work clarifies the nonequilibrium dynamics of microscopic particles moving in rarefied gases, and can improve our microscopic understanding of the collision force.
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Affiliation(s)
- Tongli Wei
- Key Laboratory of Physics and Photoelectric Information Functional Materials Sciences and Technology, North Minzu University, Yinchuan 750021, China
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000, China
| | - Xiansheng Cao
- School of Microelectronics and Control Engineering, Changzhou University, Changzhou 213164, China
| | - Decheng Ma
- Department of Physics, Shanghai University, Shanghai 200444, China
| | - Yaojin Li
- Electronic Materials Research Laboratory International Center for Dielectric Research, Xi'an Jiaotong University, Xi'an 710049, China
| | - Chenglong Jia
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000, China
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5
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Single molecule demonstration of Debye-Stokes-Einstein breakdown in polystyrene near the glass transition temperature. Nat Commun 2022; 13:3580. [PMID: 35739122 PMCID: PMC9226357 DOI: 10.1038/s41467-022-31318-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: 01/11/2022] [Accepted: 06/10/2022] [Indexed: 11/25/2022] Open
Abstract
Rotational-translational decoupling, in which translational motion is apparently enhanced over rotational motion in violation of Stokes-Einstein (SE) and Debye-Stokes-Einstein (DSE) predictions, has been observed in materials near their glass transition temperatures (Tg). This has been posited to result from ensemble averaging in the context of dynamic heterogeneity. In this work, ensemble and single molecule experiments are performed in parallel on a fluorescent probe in high molecular weight polystyrene near its Tg. Ensemble results show decoupling onset at approximately 1.15Tg, increasing to over three orders of magnitude at Tg. Single molecule measurements also show a high degree of decoupling, with typical molecules at Tg showing translational diffusion coefficients nearly 400 times higher than expected from SE/DSE predictions. At the single molecule level, higher degree of breakdown is associated with particularly mobile molecules and anisotropic trajectories, providing support for anomalous diffusion as a critical driver of rotational-translational decoupling and SE/DSE breakdown. Experiments with high-molecular-weight polystyrene provide insights into the mechanisms behind rotational-translational decoupling in glassy systems. Specifically, particularly mobile molecules exhibiting anisotropic trajectories are found to play a key role in Debye-Stokes-Einstein breakdown.
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6
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Ghahari A, Raissi H, Farzad F. Design of a new drug delivery platform based on surface functionalization 2D covalent organic frameworks. J Taiwan Inst Chem Eng 2021. [DOI: 10.1016/j.jtice.2021.05.048] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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7
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Zhao H, Zhao H. Testing the Stokes-Einstein relation with the hard-sphere fluid model. Phys Rev E 2021; 103:L030103. [PMID: 33862740 DOI: 10.1103/physreve.103.l030103] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 02/19/2021] [Indexed: 11/07/2022]
Abstract
The Stokes-Einstein (SE) relation has been widely applied to quantitatively describe the Brownian motion. Notwithstanding, here we show that even for a simple fluid, the SE relation may fail over a wide range of the Brownian particle's size. Namely, although the SE relation could be a good approximation for a large enough Brownian particle, a significant error may appear when decreasing the Brownian particle's size down to several hundred times the size of the fluid molecules, and the error increases with the decrease of the Brownian particle's size. The cause is rooted in the fact that the kinetic contribution to the diffusion coefficient is inversely proportional to the squared radius of the Brownian particle. After excluding the kinetic contribution, we show that the applicable range of the SE relation is expanded significantly.
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Affiliation(s)
- Hanqing Zhao
- Department of Physics, Xiamen University, Xiamen 361005, Fujian, China.,Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
| | - Hong Zhao
- Department of Physics, Xiamen University, Xiamen 361005, Fujian, China.,Lanzhou Center for Theoretical Physics, Lanzhou University, Lanzhou, Gansu 730000, China
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8
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Pham-Van H, Tran-Phan-Thuy L, Tran-Manh C, Do-Danh B, Luc-Huy H. Two-Dimensional Clusters of Colloidal Particles Induced by Emulsion Droplet Evaporation. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E156. [PMID: 31963178 PMCID: PMC7023411 DOI: 10.3390/nano10010156] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 01/02/2020] [Accepted: 01/02/2020] [Indexed: 11/16/2022]
Abstract
The minimization principle of the second moment of the mass distribution ( M 2 ) is responsible for the unique structure of three-dimensional clusters by using emulsion droplet evaporation. Herein we study the structure of two-dimensional clusters of colloidal particles bound at the interface of liquid droplets in the plane. We found that, differently from the three-dimensional system, the two-dimensional clusters have multiple degenerate configurations (isomers). An interesting feature of such two-dimensional clusters is that they have the same packings as those belonging to a class of geometric figures known as polyiamonds. In particular, except for the six-particle cluster, many higher order clusters of polyiamond have not been reported previously. Using a simple geometrical approach, based on the number of ways to generate a packing, we calculated the occupation probabilities of distinct isomeric clusters. The level of agreement with the results of metropolis Monte Carlo simulations was good for clusters containing up to nine particles, suggesting that our two-dimensional cluster structures are not a result of the minimization of the second moment. In addition, the structure of these clusters is somewhat insensitive to the range and depth of the interparticle potential, in good agreement with the results in the literature.
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Affiliation(s)
- Hai Pham-Van
- Department of Physics, Hanoi National University of Education, 136 Xuanthuy, Caugiay, Hanoi 100000, Vietnam
| | | | | | | | - Hoang Luc-Huy
- Department of Physics, Hanoi National University of Education, 136 Xuanthuy, Caugiay, Hanoi 100000, Vietnam
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9
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Shiba H, Kawasaki T, Kim K. Local Density Fluctuation Governs the Divergence of Viscosity Underlying Elastic and Hydrodynamic Anomalies in a 2D Glass-Forming Liquid. PHYSICAL REVIEW LETTERS 2019; 123:265501. [PMID: 31951456 DOI: 10.1103/physrevlett.123.265501] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Indexed: 06/10/2023]
Abstract
If a liquid is cooled rapidly to form a glass, its structural relaxation becomes retarded, producing a drastic increase in viscosity. In two dimensions, strong long-wavelength fluctuations persist, even at low temperature, making it difficult to evaluate the microscopic structural relaxation time. This Letter shows that, in a 2D glass-forming liquid, relative displacement between neighbor particles yields a relaxation time that grows in proportion to the viscosity. In addition to thermal elastic vibrations, hydrodynamic fluctuations are found to affect the long-wavelength dynamics, yielding a logarithmically diverging diffusivity in the long-time limit.
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Affiliation(s)
- Hayato Shiba
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - Takeshi Kawasaki
- Department of Physics, Nagoya University, Nagoya 464-8602, Japan
| | - Kang Kim
- Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, Osaka 560-8531, Japan
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10
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Ghannad Z. Fickian yet non-Gaussian diffusion in two-dimensional Yukawa liquids. Phys Rev E 2019; 100:033211. [PMID: 31639989 DOI: 10.1103/physreve.100.033211] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Indexed: 11/07/2022]
Abstract
We investigate Fickian diffusion in two-dimensional (2D) Yukawa liquids using molecular dynamics simulations. We compute the self-van Hove correlation function G_{s}(r,t) and the self-intermediate scattering function F_{s}(k,t), and we compare these functions with those obtained from mean-squared displacement (MSD) using the Gaussian approximation. According to this approximation, a linear MSD with time implies a Gaussian behavior for G_{s}(r,t) and F_{s}(k,t) at all times. Surprisingly, we find that these functions deviate from Gaussian at intermediate timescales, indicating the failure of the Gaussian approximation. Furthermore, we quantify these deviations by the non-Gaussian parameter, and we find that the deviations increase when the temperature of the liquid decreases. The origin of the non-Gaussian behavior may be the heterogeneous dynamics of dust particles observed in 2D Yukawa liquids.
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Affiliation(s)
- Zahra Ghannad
- Department of Physics, Alzahra University, P.O. Box 19938-93973, Tehran, Iran
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11
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Fatehi M, Mohebbi A, Moradi A. Understanding the structural, dynamic and thermodynamic properties of 5-Nonylsalicylaldoxime: Molecular dynamics and experimental studies. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.08.159] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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12
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Torres-Carbajal A, Castañeda-Priego R. Friction and diffusion of a nano-colloidal disk in a two-dimensional solvent with a liquid-liquid transition. Phys Chem Chem Phys 2018; 20:6917-6928. [PMID: 29464245 DOI: 10.1039/c7cp08302e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report on the friction and diffusion of a single mobile nano-colloidal disk, whose size and mass are one and two orders of magnitude, respectively, greater than the molecules of the host solvent; all particles are restricted to move in a two-dimensional space. Using molecular dynamics simulations, the variation of the transport coefficients as a function of the thermodynamic state of the supporting fluid, in particular, around those states in the neighbourhood of the liquid-liquid phase coexistence, is investigated. The diffusion coefficient is determined through the fit of the mean-square displacement at long times and with the Green-Kubo relationship for the velocity autocorrelation function, whereas the friction coefficient is computed from the correlation of the fluctuating force. From the determination of the transport properties, the applicability of the Stokes-Einstein relation in two dimensions around the second critical point is discussed.
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Affiliation(s)
- Alexis Torres-Carbajal
- 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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13
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14
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Antoine C, Talbot J. Effect of crowding and confinement on first-passage times: A model study. Phys Rev E 2016; 93:062120. [PMID: 27415221 DOI: 10.1103/physreve.93.062120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Indexed: 06/06/2023]
Abstract
We study the "color dynamics" of a hard-disk fluid confined in an annulus, as well as the corresponding hard-sphere system in three dimensions, using event-driven simulation in order to explore the effect of confinement and self-crowding on the search for targets. We compute the mean first-passage times (MFPTs) of red particles transiting from the outer to the inner boundary as well as those of blue particles passing from the inner to the outer boundary for different packing fractions and geometries. In the steady state the reaction rate, defined as the rate of collision of red particles with the inner boundary, is inversely proportional to the sum of the MFPTs. The reaction rate is wall mediated (ballistic) at low densities and diffusion controlled at higher densities and displays a maximum at intermediate densities. At moderate to high densities, the presence of layering has a strong influence on the search process. The numerical results for the reaction rate and MFPTs are compared with a ballistic model at low densities and a Smoluchowski approach with uniform diffusivities at higher densities. We discuss the reasons for the limited validity of the theoretical approaches. The maximum in the reaction rate is qualitatively well rendered by a Bosanquet-like approach that interpolates between the two regimes. Finally, we compute the position-dependent diffusivity from the MFPTs and observe that it is out of phase with the radial density.
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Affiliation(s)
- C Antoine
- Laboratoire de Physique Théorique de la Matière Condensée, UPMC, CNRS UMR 7600, Sorbonne Universités, 4 place Jussieu, 75252 Paris Cedex 05, France
| | - J Talbot
- Laboratoire de Physique Théorique de la Matière Condensée, UPMC, CNRS UMR 7600, Sorbonne Universités, 4 place Jussieu, 75252 Paris Cedex 05, France
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15
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Shin HK, Choi B, Talkner P, Lee EK. Normal versus anomalous self-diffusion in two-dimensional fluids: Memory function approach and generalized asymptotic Einstein relation. J Chem Phys 2014; 141:214112. [DOI: 10.1063/1.4902409] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Affiliation(s)
- Hyun Kyung Shin
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea
| | - Bongsik Choi
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea
| | - Peter Talkner
- Universität Augsburg, Institut für Physik, D-86135 Augsburg, Germany
- Asia Pacific Center for Theoretical Physics (APCTP), San 31, Hyoja-dong, Nam-gu, Pohang, Gyeongbuk 790-784, South Korea
| | - Eok Kyun Lee
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea
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16
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Liu B, Goree J. Perpendicular diffusion of a dilute beam of charged dust particles in a strongly coupled dusty plasma. PHYSICS OF PLASMAS 2014; 21. [DOI: 10.1063/1.4885353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
The diffusion of projectiles drifting through a target of strongly coupled dusty plasma is investigated in a simulation. A projectile's drift is driven by a constant force F. We characterize the random walk of the projectiles in the direction perpendicular to their drift. The perpendicular diffusion coefficient Dp⊥ is obtained from the simulation data. The force dependence of Dp⊥ is found to be a power law in a high force regime, but a constant at low forces. A mean kinetic energy Wp for perpendicular motion is also obtained. The diffusion coefficient is found to increase with Wp with a linear trend at higher energies, but an exponential trend at lower energies.
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Affiliation(s)
- Bin Liu
- The University of Iowa Department of Physics and Astronomy, , Iowa City, Iowa 52242, USA
| | - J. Goree
- The University of Iowa Department of Physics and Astronomy, , Iowa City, Iowa 52242, USA
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17
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Yang C, I L. Stress-induced microcracking and cooperative motion of cold dusty plasma liquids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 89:041102. [PMID: 24827183 DOI: 10.1103/physreve.89.041102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2014] [Indexed: 06/03/2023]
Abstract
We investigate the microresponse of the quasi-two-dimensional dusty plasma liquid around freezing to the shear force from a laser beam through the center of the liquid cluster. It is found that the cold liquid can be viewed as a patchwork of crystalline ordered domains (CODs) which are solidlike but can be cracked and rearranged by weak thermal agitation and external stress, through COD rotations and drifting. Under weak external stress comparable to thermal agitation, the laser zone is not the preferred region mastering cracking initiation. CODs in the laser zone can either break locally, or sustain and propagate the stress to remote regions for cracking, in the form of intermittent bursts. The COD rotation and drifting induced by the persistent torques and momentum from the stress causes the formation of the center shear band with a higher longitudinal speed. Increasing stress can enhance cracking initiation around the shear zone and then spread to other remote regions. It deteriorates the local structural order and causes strong shear banding dominated by longitudinal cooperative hopping.
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Affiliation(s)
- Chi Yang
- Department of Physics and Center for Complex Systems, National Central University, Jhongli, Taiwan 32001, Republic of China
| | - Lin I
- Department of Physics and Center for Complex Systems, National Central University, Jhongli, Taiwan 32001, Republic of China
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18
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Sengupta S, Karmakar S, Dasgupta C, Sastry S. Breakdown of the Stokes-Einstein relation in two, three, and four dimensions. J Chem Phys 2013; 138:12A548. [DOI: 10.1063/1.4792356] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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19
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Ladadwa I, Heuer A. Nonlinear response and crowding effects in microrheology. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 87:012302. [PMID: 23410326 DOI: 10.1103/physreve.87.012302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2012] [Revised: 10/31/2012] [Indexed: 06/01/2023]
Abstract
The mobility of tagged particles in a microrheological setup has been investigated via molecular dynamics simulations of a three-dimensional Lennard-Jones binary mixture. After coupling a small number of particles to a constant external driving force, the drift velocity and other observables of the dragged probe particles are reported in the linear and nonlinear response regime. In the nonlinear regime significant crowding effects are observed, thereby creating stringlike structures. Formation of the strings further enhances the nonlinear effects. A systematic study of these effects' dependence on temperature and total number of driven probe atoms is presented.
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Affiliation(s)
- I Ladadwa
- Westfälische Wilhelms-Universität Münster, Institut für physikalische Chemie, Corrensstrasse 30, 48149 Münster, Germany.
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20
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Yang C, Io CW, I L. Cooperative-motion-induced structural evolution in dusty-plasma liquids with microheterogeneity: rupture, rotation, healing, and growth of ordered domains. PHYSICAL REVIEW LETTERS 2012; 109:225003. [PMID: 23368131 DOI: 10.1103/physrevlett.109.225003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Indexed: 06/01/2023]
Abstract
The cooperative motion induced structural evolution of the liquid with microheterogeneity is investigated in quasi-2D dusty plasma liquids, through direct optical visualization. A novel bond-dynamics analysis is used to further classify the robust cooperative 2D clusters into static, rotating, and drifting patches, beyond the earlier findings of the cooperative hopping strings and bands. The relative motion between two adjacent clusters causes the formation of a fractal network with narrow shear strips along the cluster interface. The rotation of the large ordered patch through rupturing into multiple rotating patches followed by the healing process, and the growth to a larger ordered patch by aligning the different lattice orientations of the adjacent ordered domains through patch rupturing, rotation, drifting, and merging are the key processes for the microstructural evolution.
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Affiliation(s)
- Chi Yang
- Department of Physics and Center for Complex Systems, National Central University, Jhongli, Taiwan 32001, Republic of China
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21
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Su YS, Io CW, I L. Transient slowing down relaxation dynamics of the supercooled dusty plasma liquid after quenching. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:016405. [PMID: 23005548 DOI: 10.1103/physreve.86.016405] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2011] [Indexed: 06/01/2023]
Abstract
The spatiotemporal evolutions of microstructure and motion in the transient relaxation toward the steady supercooled liquid state after quenching a dusty plasma Wigner liquid, formed by charged dust particles suspended in a low pressure discharge, are experimentally investigated through direct optical microscopy. It is found that the quenched liquid slowly evolves to a colder state with more heterogeneities in structure and motion. Hopping particles and defects appear in the form of clusters with multiscale cluster size distributions. Via the structure rearrangement induced by the reduced thermal agitation from the cold thermal bath after quenching, the temporarily stored strain energy can be cascaded through the network to different newly distorted regions and dissipated after transferring to nonlinearly coupled motions with different scales. It leads to the observed self-similar multiscale slowing down relaxation with power law increases of structural order and structural relaxation time, the similar power law decreases of particle motions at different time scales, and the stronger and slower fluctuations with increasing waiting time toward the new steady state.
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Affiliation(s)
- Yen-Shuo Su
- Department of Physics and Center for Complex Systems, National Central University, Jhongli, Taiwan 32001, Republic of China
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Lü Y, Cheng H, Chen M. A molecular dynamics examination of the relationship between self-diffusion and viscosity in liquid metals. J Chem Phys 2012; 136:214505. [DOI: 10.1063/1.4723683] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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23
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Khrustalyov YV, Vaulina OS. Numerical simulations of thermal conductivity in dissipative two-dimensional Yukawa systems. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:046405. [PMID: 22680584 DOI: 10.1103/physreve.85.046405] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Revised: 02/06/2012] [Indexed: 06/01/2023]
Abstract
Numerical data on the heat transfer constants in two-dimensional Yukawa systems were obtained. Numerical study of the thermal conductivity and diffusivity was carried out for the equilibrium systems with parameters close to conditions of laboratory experiments with dusty plasma. For calculations of heat transfer constants the Green-Kubo formulas were used. The influence of dissipation (friction) on the heat transfer processes in nonideal systems was investigated. The approximation of the coefficient of thermal conductivity is proposed. Comparison of the obtained results to the existing experimental and numerical data is discussed.
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24
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Feng Y, Goree J, Liu B, Cohen EGD. Green-Kubo relation for viscosity tested using experimental data for a two-dimensional dusty plasma. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:046412. [PMID: 22181288 DOI: 10.1103/physreve.84.046412] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Revised: 09/16/2011] [Indexed: 05/31/2023]
Abstract
The theoretical Green-Kubo relation for viscosity is tested using experimentally obtained data. In a dusty plasma experiment, micron-sized dust particles are introduced into a partially ionized argon plasma, where they become negatively charged. They are electrically levitated to form a single-layer Wigner crystal, which is subsequently melted using laser heating. In the liquid phase, these dust particles experience interparticle electric repulsion, laser heating, and friction from the ambient neutral argon gas, and they can be considered to be in a nonequilibrium steady state. Direct measurements of the positions and velocities of individual dust particles are then used to obtain a time series for an off-diagonal element of the stress tensor and its time autocorrelation function. This calculation also requires the interparticle potential, which was not measured experimentally but was obtained using a Debye-Hückel-type model with experimentally determined parameters. Integrating the autocorrelation function over time yields the viscosity for shearing motion among dust particles. The viscosity so obtained is found to agree with results from a previous experiment using a hydrodynamical Navier-Stokes equation. This comparison serves as a test of the Green-Kubo relation for viscosity. Our result is also compared to the predictions of several simulations.
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Affiliation(s)
- Yan Feng
- Department of Physics and Astronomy, The University of Iowa, Iowa City, Iowa 52242, USA.
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25
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Kong W, Liu S, Hu B, Wang L. Diffusive and structural properties in a binary mixture of charged particles. Phys Rev E 2009; 80:036406. [PMID: 19905229 DOI: 10.1103/physreve.80.036406] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2009] [Revised: 08/19/2009] [Indexed: 11/07/2022]
Abstract
Diffusive and structural properties in the binary mixture of charged particles are investigated based on the molecular dynamical simulation. It is shown that the particles with higher charge enhance or weaken the diffusion of the whole system depending on the coupling strength, and regimes of subdiffusion as well as normal diffusion are identified. The nonmonotonous diffusion, i.e., the diffusion at first is increased and then is decreased with increasing the higher charged particles, is strongest close to the phase from liquidlike state to solidlike state. Stronger coupling and lower concentration of higher charged particles are in favor of the formation of ordered shells centered at the higher charged particles.
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Affiliation(s)
- Wei Kong
- Physics Department, Nankai University, Tianjin, China
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26
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Io CW, I L. Steady-shear-enhanced microdiffusion with multiple time scales of confined, mesoscopic, two-dimensional dusty-plasma liquids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 80:036401. [PMID: 19905224 DOI: 10.1103/physreve.80.036401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2009] [Indexed: 05/28/2023]
Abstract
We experimentally investigate the multitime scale diffusion and the spatiotemporal behaviors of the degrees of enhancement for the longitudinal and the transverse diffusions in a confined mesoscopic quasi-two-dimensional dusty-plasma liquid sheared by two parallel counterpropagating laser beams. The steady external drive directly enhances the longitudinal cooperative hopping, associated with the shear bands that have high shear rate near boundaries. It drastically excites the slow hopping modes to high fluctuation level in the outer band region, accompanied by the enhanced superdiffusion. Through cascaded many-body interaction, the excitation flows from the outer region toward the center region, from the longitudinal modes to the transverse mode, and from the slow hopping modes to the fast caging modes, which are in better contact with the thermal bath. It causes the weaker enhancement of fluctuation level, and diffusion for the center region and the fast modes. The boundary confinement further breaks the system symmetry and enhances anisotropy. It has much stronger effect on the suppression of the transverse hopping modes than the longitudinal hopping mode. The degrees of enhancement of the fluctuations by the shear stress are highly anisotropic for the large amplitude slow modes, especially in the outer region but are more isotropic in the inner band.
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Affiliation(s)
- Chong-Wai Io
- Department of Physics and Center for Complex Systems, National Central University, Chungli, Taiwan 32054, Republic of China
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27
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Hou LJ, Piel A, Shukla PK. Self-diffusion in 2D dusty-plasma liquids: numerical-simulation results. PHYSICAL REVIEW LETTERS 2009; 102:085002. [PMID: 19257746 DOI: 10.1103/physrevlett.102.085002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2008] [Indexed: 05/27/2023]
Abstract
We perform Brownian dynamics simulations for studying the self-diffusion in two-dimensional (2D) dusty-plasma liquids, in terms of both mean-square displacement and the velocity autocorrelation function (VAF). Superdiffusion of charged dust particles has been observed to be the most significant at an infinitely small damping rate gamma for intermediate coupling strength, where the long-time asymptotic behavior of VAF is found to be the product of t;{-1} and exp(-gammat). The former represents the prediction of early theories in 2D simple liquids and the latter the VAF of a free Brownian particle. This leads to a smooth transition from superdiffusion to normal diffusion, and then to subdiffusion with an increase of the damping rate. These results well explain the seemingly contradictory observations scattered in recent classical molecular dynamics simulations and experiments of dusty plasmas.
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Affiliation(s)
- Lu-Jing Hou
- IEAP, Christian-Albrechts Universität zu Kiel, D-24098 Kiel, Germany
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28
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Donkó Z, Goree J, Hartmann P, Liu B. Time-correlation functions and transport coefficients of two-dimensional Yukawa liquids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 79:026401. [PMID: 19391849 DOI: 10.1103/physreve.79.026401] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2007] [Revised: 10/10/2008] [Indexed: 05/27/2023]
Abstract
The existence of coefficients for diffusion, viscosity, and thermal conductivity is examined for two-dimensional (2D) liquids. Equilibrium molecular dynamics simulations are performed using a Yukawa potential and the long-time behavior of autocorrelation functions is tested. Advances reported here as compared to previous 2D Yukawa liquid simulations include an assessment of the thermal conductivity, using a larger system size to allow meaningful examination of longer times, and development of improved analysis methods. We find that the transport coefficient exists for diffusion at high temperature and viscosity at low temperature, but not in the opposite limits. The thermal conductivity coefficient does not appear to exist at high temperature. Further advances in computing power could improve these assessments by allowing even larger system sizes and longer time series.
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Affiliation(s)
- Z Donkó
- Research Institute for Solid State Physics and Optics of the Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 49, Hungary
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29
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Yang J, Zhao J, Han CC. Lateral Mobility of Single Chains at a Liquid Polymer Interface. Macromolecules 2008. [DOI: 10.1021/ma8015135] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jingfa Yang
- Beijing Laboratory of Molecular Sciences, Joint Laboratory of Polymer Sciences and Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Jiang Zhao
- Beijing Laboratory of Molecular Sciences, Joint Laboratory of Polymer Sciences and Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Charles C. Han
- Beijing Laboratory of Molecular Sciences, Joint Laboratory of Polymer Sciences and Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
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30
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Liu B, Goree J, Feng Y. Non-Gaussian statistics and superdiffusion in a driven-dissipative dusty plasma. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 78:046403. [PMID: 18999539 DOI: 10.1103/physreve.78.046403] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2008] [Indexed: 05/27/2023]
Abstract
Particle random motion can exhibit both anomalous diffusion and non-Gaussian statistics in some physical systems. Anomalous diffusion is quantified by a deviation from alpha=1 in a power law for a particle's mean-square displacement, MSD proportional, variant(Deltat)alpha. A deviation from Gaussian statistics for a probability distribution function (PDF) is quantified by fitting to a kappa function or Tsallis distribution, with a fit parameter q. We report an experiment and simulations to test a theory that connects anomalous diffusion and non-Gaussian statistics. In the experiment, a single-layer dusty plasma, which behaved as a two-dimensional (2D) driven-dissipative system, had a non-Gaussian PDF. By adjusting an externally applied laser heating, q was varied over a wide range. A correlation between the deviations from Gaussian statistics and normal diffusion for a 2D liquid was found in the experiment. This correlation indicates a connection between anomalous diffusion and non-Gaussian statistics. However, such a connection is lacking in equilibrium 2D Yukawa liquids, as demonstrated in numerical simulations.
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Affiliation(s)
- Bin Liu
- Department of Physics and Astronomy, The University of Iowa, Iowa City, Iowa 52242, USA
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31
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Donkó Z, Hartmann P. Shear viscosity of strongly coupled Yukawa liquids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 78:026408. [PMID: 18850947 DOI: 10.1103/physreve.78.026408] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2008] [Indexed: 05/26/2023]
Abstract
We present molecular-dynamics calculations of the shear viscosity of three-dimensional strongly coupled Yukawa liquids which are frequently used as a model system of complex plasmas. The results obtained using two independent nonequilibrium simulation methods are critically compared with each other and with earlier published data for a wide range of plasma coupling (Gamma) and screening (kappa) parameters. The non-Newtonian behavior of the liquid, manifested as a decrease of the shear viscosity with increasing shear rate (shear thinning), and the validity of the Stokes-Einstein relation at high coupling strength are also demonstrated.
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Affiliation(s)
- Z Donkó
- Research Institute for Solid State Physics and Optics of the Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 49, Hungary
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32
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Liu B, Goree J. Superdiffusion and non-Gaussian statistics in a driven-dissipative 2D dusty plasma. PHYSICAL REVIEW LETTERS 2008; 100:055003. [PMID: 18352381 DOI: 10.1103/physrevlett.100.055003] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2007] [Indexed: 05/26/2023]
Abstract
Anomalous diffusion and non-Gaussian statistics are detected experimentally in a two-dimensional driven-dissipative system. A single-layer dusty plasma suspension with a Yukawa interaction and frictional dissipation is heated with laser radiation pressure to yield a structure with liquid ordering. Analyzing the time series for mean-square displacement, superdiffusion is detected at a low but statistically significant level over a wide range of temperatures. The probability distribution function fits a Tsallis distribution, yielding q, a measure of nonextensivity for non-Gaussian statistics.
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Affiliation(s)
- Bin Liu
- Department of Physics and Astronomy, The University of Iowa, Iowa City, Iowa 52242, USA
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33
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Huang YH, I L. Memory and persistence correlation of microstructural fluctuations in two-dimensional dusty plasma liquids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 76:016403. [PMID: 17677575 DOI: 10.1103/physreve.76.016403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2007] [Revised: 05/09/2007] [Indexed: 05/16/2023]
Abstract
We investigate the temporal memory and persistence time correlations of microstructural order fluctuations in quasi-two-dimensional dusty plasma liquids through directly monitoring particle positions. The persistence length of the ordered and the disordered microstates both follow power-law distribution for the cold liquid. The correlation probabilities of the persistence lengths in different pairs of fluctuating cycles show that an order-disorder-order and a disorder-order-disorder sequence are more likely to have the long-short-long or short-long-short persistent lengths combination. The persistence time correlation lasts for several fluctuating cycles. The correlation memory is stored in the surrounding heterogeneous network through mutual coupling. Increasing thermal noise level deteriorates the memory and leads to the less correlated stretched exponential distribution of the persistent length.
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Affiliation(s)
- Yu-Hsuan Huang
- Department of Physics and Center for Complex Systems, National Central University, Jhongli, Taiwan 32001, Republic of China
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34
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Reichhardt C, Olson Reichhardt CJ. Defect fluctuations and lifetimes in disordered Yukawa systems. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 75:051407. [PMID: 17677065 DOI: 10.1103/physreve.75.051407] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2006] [Indexed: 05/16/2023]
Abstract
We examine the time-dependent defect fluctuations and lifetimes for a bidisperse disordered assembly of Yukawa particles. At high temperatures, the noise spectrum of fluctuations is white and the coordination number lifetimes have a stretched exponential distribution. At lower temperatures, the system dynamically freezes, the defect fluctuations exhibit a 1/f spectrum, and there is a power law distribution of the coordination number lifetimes. Our results indicate that topological defect fluctuations may be a useful way to characterize disordered systems.
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Affiliation(s)
- C Reichhardt
- Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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35
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Ivanov Y, Melzer A. Particle positioning techniques for dusty plasma experiments. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2007; 78:033506. [PMID: 17411184 DOI: 10.1063/1.2714050] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Video microscopy is a widely applied diagnostic to investigate the structure and the dynamics of particles in dusty plasmas. Reliable algorithms are required to accurately recover particle positions from the camera images. Here, four different particle positioning techniques have been tested on artificial and experimental data of dusty plasma situations. Two methods that rely on pixel-intensity thresholds were found to be strongly affected by pixel-locking errors and by noise. Two other methods-one applying spatial bandpass filters and the other fitting polynomials to the intensity pattern-yield subpixel resolution under various conditions. These two methods have been shown to be ideally suited to recover particle positions even from small-scale fluctuations that are used to derive the normal mode spectra of finite dust clusters.
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Affiliation(s)
- Yuriy Ivanov
- Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald, Germany.
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36
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Liu B, Goree J. Superdiffusion in two-dimensional Yukawa liquids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 75:016405. [PMID: 17358266 DOI: 10.1103/physreve.75.016405] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2006] [Indexed: 05/14/2023]
Abstract
Superdiffusion of two-dimensional (2D) liquids was studied using an equilibrium molecular dynamics simulation. At intermediate temperatures, the mean-squared displacement, probability distribution function (PDF), and velocity autocorrelation function (VACF) all indicate superdiffusion; the VACF has a long-time tail; and the PDF indicates no Lévy flights. These effects are predicted to occur in 2D dusty plasmas and other 2D liquids that can be modeled with a long-range repulsive potential.
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Affiliation(s)
- Bin Liu
- Department of Physics and Astronomy, The University of Iowa, Iowa City, Iowa 52242, USA
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37
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Sharma M, Yashonath S. Breakdown of the Stokes−Einstein Relationship: Role of Interactions in the Size Dependence of Self-Diffusivity. J Phys Chem B 2006; 110:17207-11. [PMID: 16928019 DOI: 10.1021/jp064364a] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Einstein and others derived the reciprocal dependence of the self-diffusivity D on the solute radius r(u) for large solutes based on kinetic theory. We examine here (a) the range of r(u) over which Stokes-Einstein (SE) dependence is valid and (b) the precise dependence for small solutes outside of the SE regime. We show through molecular dynamics simulations that there are two distinct regimes for smaller solutes: (i) the interaction or Levitation effect (LE) regime for solutes of intermediate size and (ii) the D proportional, variant 1/r(u)(2) for still smaller solutes. We show that as the solute-solvent size ratio decreases, the breakdown in the Stokes-Einstein relationship leading to the LE regime has its origin in dispersion interaction between the solute and the solvent. These results explain reports of enhanced solute diffusion in solvents existing in the literature seen for small solutes for which no explanation exists.
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Affiliation(s)
- Manju Sharma
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore-560012, India
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