1
|
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.
Collapse
Affiliation(s)
- Zahra Ghannad
- Department of Physics, Alzahra University, P.O. Box 19938-93973, Tehran, Iran
| |
Collapse
|
2
|
Feng Y, Lin W, Murillo MS. Viscosity of two-dimensional strongly coupled dusty plasma modified by a perpendicular magnetic field. Phys Rev E 2018; 96:053208. [PMID: 29347770 DOI: 10.1103/physreve.96.053208] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Indexed: 11/07/2022]
Abstract
Transport properties of two-dimensional (2D) strongly coupled dusty plasmas have been investigated in detail, but never for viscosity with a strong perpendicular magnetic field; here, we examine this scenario using Langevin dynamics simulations of 2D liquids with a binary Yukawa interparticle interaction. The shear viscosity η of 2D liquid dusty plasma is estimated from the simulation data using the Green-Kubo relation, which is the integration of the shear stress autocorrelation function. It is found that, when a perpendicular magnetic field is applied, the shear viscosity of 2D liquid dusty plasma is modified substantially. When the magnetic field is increased, its viscosity increases at low temperatures, while at high temperatures its viscosity diminishes. It is determined that these different variational trends of η arise from the different behaviors of the kinetic and potential parts of the shear stress under external magnetic fields.
Collapse
Affiliation(s)
- Yan Feng
- Center for Soft Condensed Matter Physics and Interdisciplinary Research, College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006, China
| | - Wei Lin
- Center for Soft Condensed Matter Physics and Interdisciplinary Research, College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006, China
| | - M S Murillo
- Department of Computational Mathematics, Science and Engineering, Michigan State University, East Lansing, Michigan 48824, USA
| |
Collapse
|
3
|
Dzhumagulova KN, Masheyeva RU, Ott T, Hartmann P, Ramazanov TS, Bonitz M, Donkó Z. Cage correlation and diffusion in strongly coupled three-dimensional Yukawa systems in magnetic fields. Phys Rev E 2016; 93:063209. [PMID: 27415379 DOI: 10.1103/physreve.93.063209] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Indexed: 06/06/2023]
Abstract
The influence of an external homogeneous magnetic field on the quasilocalization of the particles-characterized quantitatively by cage correlation functions-in strongly coupled three-dimensional Yukawa systems is investigated via molecular dynamics computer simulations over a wide domain of the system parameters (coupling and screening strengths, and magnetic field). The caging time is found to be enhanced by the magnetic field B. The anisotropic migration of the particles in the presence of magnetic field is quantified via computing directional correlation functions, which indicate a more significant increase of localization in the direction perpendicular to B, while a moderate increase is also found along the B field lines. Associating the particles' escapes from the cages with jumps of a characteristic length, a connection is found with the diffusion process: the diffusion coefficients derived from the decay time of the directional correlation functions in both the directions perpendicular to and parallel with B are in very good agreement with respective diffusion coefficients values obtained from their usual computation based on the mean-squared displacement of the particles.
Collapse
Affiliation(s)
- K N Dzhumagulova
- IETP, Al Farabi Kazakh National University, 71, al Farabi Avenue, Almaty, 050040, Kazakhstan
| | - R U Masheyeva
- IETP, Al Farabi Kazakh National University, 71, al Farabi Avenue, Almaty, 050040, Kazakhstan
| | - T Ott
- Institute for Theoretical Physics and Astrophysics, Christian-Albrechts-University Kiel, Leibnizstrasse 15, 24098 Kiel, Germany
| | - P Hartmann
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, H-1121 Budapest, Konkoly-Thege Miklós Street 29-33, Hungary
| | - T S Ramazanov
- IETP, Al Farabi Kazakh National University, 71, al Farabi Avenue, Almaty, 050040, Kazakhstan
| | - M Bonitz
- Institute for Theoretical Physics and Astrophysics, Christian-Albrechts-University Kiel, Leibnizstrasse 15, 24098 Kiel, Germany
| | - Z Donkó
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, H-1121 Budapest, Konkoly-Thege Miklós Street 29-33, Hungary
| |
Collapse
|
4
|
Barocchi F, Guarini E, Bafile U. Exponential series expansion for correlation functions of many-body systems. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:032106. [PMID: 25314394 DOI: 10.1103/physreve.90.032106] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Indexed: 06/04/2023]
Abstract
We demonstrate that in Hamiltonian many-body systems at equilibrium, any kind of time dependent correlation function c(t) can always be expanded in a series of (complex) exponential functions of time when its Laplace transform C̃(z) has single poles. The characteristic frequencies can be identified as the eigenfrequencies of the correlation. This is done without introducing the concepts of fluctuating forces and memory functions, due to Mori and Zwanzig and extensively used in the literature in the last decades. Our method is based on a different projection technique in the Hilbert space S of the system and shows that appropriate approximations of the exponential series are related to the contraction of S to a finite, usually small, number of dimensions. The time dependence of correlation functions is always described in detail by a multiple-exponential functionality also at long times. This result is therefore also valid for correlation functions of many-body Hamiltonian systems for which a power-law dependence, observed in restricted time ranges and predicted to be the asymptotic one, can be considered at most as a useful approximate modeling of long-time behavior.
Collapse
Affiliation(s)
- Fabrizio Barocchi
- Dipartimento di Fisica e Astronomia, Università di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino, Italy
| | - Eleonora Guarini
- Dipartimento di Fisica e Astronomia, Università di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino, Italy
| | - Ubaldo Bafile
- Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy
| |
Collapse
|
5
|
Magyar P, Donkó Z, Kalman GJ, Golden KI. Linear and quadratic static response functions and structure functions in Yukawa liquids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:023102. [PMID: 25215834 DOI: 10.1103/physreve.90.023102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Indexed: 06/03/2023]
Abstract
We compute linear and quadratic static density response functions of three-dimensional Yukawa liquids by applying an external perturbation potential in molecular dynamics simulations. The response functions are also obtained from the equilibrium fluctuations (static structure factors) in the system via the fluctuation-dissipation theorems. The good agreement of the quadratic response functions, obtained in the two different ways, confirms the quadratic fluctuation-dissipation theorem. We also find that the three-point structure function may be factorizable into two-point structure functions, leading to a cluster representation of the equilibrium triplet correlation function.
Collapse
Affiliation(s)
- Péter Magyar
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, H-1121 Budapest, Konkoly-Thege Miklós Street 29-33, Hungary
| | - Zoltán Donkó
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, H-1121 Budapest, Konkoly-Thege Miklós Street 29-33, Hungary and Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - Gabor J Kalman
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - Kenneth I Golden
- Department of Mathematics and Statistics, and Department of Physics, University of Vermont, Burlington, Vermont USA
| |
Collapse
|
6
|
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.
Collapse
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
| |
Collapse
|
7
|
Schwabe M, Graves DB. Simulating the dynamics of complex plasmas. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:023101. [PMID: 24032946 DOI: 10.1103/physreve.88.023101] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Indexed: 06/02/2023]
Abstract
Complex plasmas are low-temperature plasmas that contain micrometer-size particles in addition to the neutral gas particles and the ions and electrons that make up the plasma. The microparticles interact strongly and display a wealth of collective effects. Here we report on linked numerical simulations that reproduce many of the experimental results of complex plasmas. We model a capacitively coupled plasma with a fluid code written for the commercial package comsol. The output of this model is used to calculate forces on microparticles. The microparticles are modeled using the molecular dynamics package lammps, which we extended to include the forces from the plasma. Using this method, we are able to reproduce void formation, the separation of particles of different sizes into layers, lane formation, vortex formation, and other effects.
Collapse
Affiliation(s)
- M Schwabe
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, USA and Max Planck Institute for Extraterrestrial Physics, P.O. Box 1312, Giessenbachstraße, 85741 Garching, Germany
| | | |
Collapse
|
8
|
Feng Y, Goree J, Liu B. Longitudinal viscosity of two-dimensional Yukawa liquids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 87:013106. [PMID: 23410445 DOI: 10.1103/physreve.87.013106] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Indexed: 06/01/2023]
Abstract
The longitudinal viscosity η(l) is obtained for a two-dimensional (2D) liquid using a Green-Kubo method with a molecular dynamics simulation. The interparticle potential used has the Debye-Hückel or Yukawa form, which models a 2D dusty plasma. The longitudinal η(l) and shear η(s) viscosities are found to have values that match very closely, with only negligible differences for the entire range of temperatures that is considered. For a 2D Yukawa liquid, the bulk viscosity η(b) is determined to be either negligibly small or not a meaningful transport coefficient.
Collapse
Affiliation(s)
- Yan Feng
- Department of Physics and Astronomy, The University of Iowa, Iowa City, Iowa 52242, USA.
| | | | | |
Collapse
|
9
|
Feng Y, Goree J, Liu B. Observation of temperature peaks due to strong viscous heating in a dusty plasma flow. PHYSICAL REVIEW LETTERS 2012; 109:185002. [PMID: 23215286 DOI: 10.1103/physrevlett.109.185002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Indexed: 06/01/2023]
Abstract
Profound temperature peaks are observed in regions of high velocity shear in a 2D dusty plasma experiment with laser-driven flow. These are attributed to viscous heating, which occurs due to collisional scattering in a shear flow. Using measurements of viscosity, thermal conductivity, and spatial profiles of flow velocity and temperature, we determine three dimensionless numbers: Brinkman, Br = 0.5; Prandtl, Pr = 0.09; and Eckert, Ec = 5.7. The large value of Br indicates significant viscous heating that is consistent with the observed temperature peaks.
Collapse
Affiliation(s)
- Yan Feng
- Department of Physics and Astronomy, The University of Iowa, Iowa City, Iowa 52242, USA.
| | | | | |
Collapse
|
10
|
Feng Y, Goree J, Liu B. Energy transport in a shear flow of particles in a two-dimensional dusty plasma. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:056403. [PMID: 23214892 DOI: 10.1103/physreve.86.056403] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Indexed: 06/01/2023]
Abstract
A shear flow of particles in a laser-driven two-dimensional (2D) dusty plasma is observed in a study of viscous heating and thermal conduction. Video imaging and particle tracking yields particle velocity data, which we convert into continuum data, presented as three spatial profiles: mean particle velocity (i.e., flow velocity), mean-square particle velocity, and mean-square fluctuations of particle velocity. These profiles and their derivatives allow a spatially resolved determination of each term in the energy and momentum continuity equations, which we use for two purposes. First, by balancing these terms so that their sum (i.e., residual) is minimized while varying viscosity η and thermal conductivity κ as free parameters, we simultaneously obtain values for η and κ in the same experiment. Second, by comparing the viscous heating and thermal conduction terms, we obtain a spatially resolved characterization of the viscous heating.
Collapse
Affiliation(s)
- Yan Feng
- Department of Physics and Astronomy, The University of Iowa, Iowa City, Iowa 52242, USA.
| | | | | |
Collapse
|
11
|
Duan W, Ibele M, Liu R, Sen A. Motion analysis of light-powered autonomous silver chloride nanomotors. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2012; 35:77. [PMID: 22926808 DOI: 10.1140/epje/i2012-12077-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Revised: 06/07/2012] [Accepted: 07/04/2012] [Indexed: 05/12/2023]
Abstract
Powered by UV light, nano/micrometer-sized silver chloride particles exhibit autonomous movement and form "schools" in aqueous solution, i.e. regions in which the number density of particles is significantly higher than the global average. In this paper, the silver chloride particles in such a system are classified by their proximity to other AgCl particles--be they isolated, coupled or schooled--and their motion paths are tracked and analyzed. By plotting time-averaged mean squared displacements of each particle over various time intervals from 0.1 s to 15.0 s, we discover different diffusive behaviors for the three classes of silver chloride particles.
Collapse
Affiliation(s)
- W Duan
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | | | | | | |
Collapse
|
12
|
Ott T, Bonitz M. Diffusion in a strongly coupled magnetized plasma. PHYSICAL REVIEW LETTERS 2011; 107:135003. [PMID: 22026863 DOI: 10.1103/physrevlett.107.135003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2011] [Indexed: 05/31/2023]
Abstract
A first-principles study of diffusion in a strongly coupled one-component plasma in a magnetic field B is presented. As in a weakly coupled plasma, the diffusion coefficient perpendicular to the field exhibits a Bohm-like 1/B behavior in the strong-field limit but its overall scaling is substantially different. The diffusion coefficient parallel to the field is strongly affected by the field as well and also approaches a 1/B scaling, in striking contrast to earlier predictions.
Collapse
Affiliation(s)
- T Ott
- Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, Germany
| | | |
Collapse
|
13
|
Hartmann P, Sándor MC, Kovács A, Donkó Z. Static and dynamic shear viscosity of a single-layer complex plasma. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:016404. [PMID: 21867319 DOI: 10.1103/physreve.84.016404] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 06/21/2011] [Indexed: 05/31/2023]
Abstract
The static and dynamic (complex) shear viscosity of a single-layer dusty plasma is measured by applying, respectively, a stationary and a periodically modulated shear stress, induced by the light pressure of manipulating laser beams. Under static conditions we observe a decrease of the viscosity with increasing shear rate, the so-called shear-thinning behavior. Under oscillating shear both the magnitude and the ratio of the dissipative and elastic contributions to the complex viscosity show strong frequency dependence, as the system changes from viscous to elastic in nature with increasing excitation frequency. Accompanying molecular dynamics simulations explain and support the experimental observations.
Collapse
Affiliation(s)
- Peter Hartmann
- Research Institute for Solid State Physics and Optics of the Hungarian Academy of Sciences, Budapest, Hungary
| | | | | | | |
Collapse
|
14
|
Ott T, Bonitz M, Hartmann P, Donkó Z. Higher harmonics of the magnetoplasmon in strongly coupled Coulomb and Yukawa systems. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 83:046403. [PMID: 21599312 DOI: 10.1103/physreve.83.046403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Indexed: 05/30/2023]
Abstract
The generation of higher harmonics of the magnetoplasmon frequency which has recently been reported in strongly coupled two-dimensional Yukawa systems is investigated in detail and, in addition, extended to two-dimensional Coulomb systems. We observe higher harmonics over a much larger frequency range than before and compare the theoretical prediction with the simulations. The influence of the coupling, structure, and thermal energy on the excitation of these modes is examined in detail. We also report on the effect of friction on the mode spectra to make predictions about the experimental observability of this new effect.
Collapse
Affiliation(s)
- T Ott
- Christian-Albrechts-Universität zu Kiel, Institut für Theoretische Physik und Astrophysik, Leibnizstraße 15, D-24098 Kiel, Germany
| | | | | | | |
Collapse
|
15
|
Land V, Matthews LS, Hyde TW, Bolser D. Fluid modeling of void closure in microgravity noble gas complex plasmas. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 81:056402. [PMID: 20866339 DOI: 10.1103/physreve.81.056402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Revised: 03/25/2010] [Indexed: 05/29/2023]
Abstract
A self-consistent dusty plasma fluid model has been extended to incorporate all the noble gases as the carrier gas. An analysis of void closure in complex plasma composed of these gases over a wide range of experimental parameters is presented. Driving potential-pressure maps are constructed, which show the range in parameter space where isotropic void-free dust crystals can be expected, where a void is to be expected and where the discharge is expected to extinguish.
Collapse
Affiliation(s)
- Victor Land
- Center for Astrophysics, Space Physics and Engineering Research, Baylor University, Waco, Texas 76798, USA.
| | | | | | | |
Collapse
|
16
|
Ott T, Bonitz M. Is diffusion anomalous in two-dimensional Yukawa liquids? PHYSICAL REVIEW LETTERS 2009; 103:195001. [PMID: 20365932 DOI: 10.1103/physrevlett.103.195001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Revised: 10/26/2009] [Indexed: 05/29/2023]
Abstract
There have recently been many predictions of "superdiffusion" in two-dimensional strongly coupled Yukawa systems, both by computer simulations and in dusty plasma experiments, with substantially varying diffusion exponents. Here we show that the results crucially depend on the strength of dissipation and the time instant of the measurement. For sufficiently large friction even subdiffusion is possible. However, there are strong indications that, in the long-time limit, anomalous diffusion vanishes and the system returns to normal diffusion, for dissipative as well as for frictionless systems.
Collapse
Affiliation(s)
- T Ott
- Christian-Albrechts-Universität zu Kiel, Institut für Theoretische Physik und Astrophysik, Leibnizstrasse 15, 24098 Kiel, Germany
| | | |
Collapse
|
17
|
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.
Collapse
Affiliation(s)
- Lu-Jing Hou
- IEAP, Christian-Albrechts Universität zu Kiel, D-24098 Kiel, Germany
| | | | | |
Collapse
|
18
|
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.
Collapse
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
| | | | | | | |
Collapse
|