Collective dynamics in liquid aluminum near the melting temperature: Theory and computer simulation

Мокшин, А. В.; Yulmetyev, Renat M.; Хуснутдинов, Р. М.; Hänggi, Peter

doi:10.1134/s1063776106120028

Cited by 28 publications

(23 citation statements)

References 29 publications

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“…Within such the ranges, the description of the proper dynamics is relevant if it is performed in terms of two-, three-and four-particle distribution functions, which are contained in the first four frequency parameters, ∆ ν , ν = 1, 2, 3, 4. Moreover, the treatment of experimental I(k, ω)-data of inelastic X-ray scattering [30] as well as the numerical molecular dynamics simulations results for liquid alkali metals near melting [23,31,32] indicate that there is the correspondence for this range of wave number:…”

Section: Microscopic Dynamics At Wave Numbers K ≤ Kmmentioning

confidence: 96%

Relaxation Processes in Many Particle Systems -- Recurrence Relations Approach

Мокшин¹

2013

DNC

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The general scheme for the treatment of relaxation processes and temporal autocorrelations of dynamical variables for many particle systems is presented in framework of the recurrence relations approach. The time autocorrelation functions and/or their spectral characteristics, which are measurable experimentally (for example, due to spectroscopy techniques) and accessible from particle dynamics simulations, can be found by means of this approach, the main idea of which is the estimation of the so-called frequency parameters. Model cases with the exact and approximative solutions are given and discussed. I. INTRODUCTIONRelaxation processes, which emerge in many particle systems, are characterized by highly nontrivial features even for the cases of the well-known simplified models [1]. So, for example, the ideal gas dynamics at the drive by external fields exhibit the non-Markovian (memory) effects [2] as well as the manifestations of anomalous transport [3], whilst the chain of coupled harmonic oscillators can display the nonlinear dynamics [4] with stochastic resonance peculiarities [5]. At the presence of complicated fields of interactions in many particle systems together with structural disorder and intricate spatiotemporal correlations allows one to recognize these as the complex systems. Thus, dense liquids, structural and spin glasses, foams, emulsions and colloidal gels are the typical examples of the physical complex systems, which combine the complicated dynamics together with the structural inhomogeneity [6].From theoretical standpoint, the description of many particle dynamics reduces oneself into a unified fashion at the applying the mathematical language of the distributions, the correlation and relaxation functions, as well as the Green functions, that provide a statistical treatment to some extent. Berne and Harp marked the significance of time correlation functions in the consideration of dynamic processes by the phrase [7]: ". . . time correlation functions have done for the theory of time-dependent processes what the partitions functions have done for the equilibrium theory. The time-dependent problem has became well defined . . . ". These enthusiastic words become more clear and accepted, if one takes into account that the correlation functions appear to be directly related with the experimentally measured quantities due to Kubo's linear response theory [8] as well as by means of nonlinear response approach [9], which obtained recently a rapid development. Importantly, the time correlation functions are associated with the concrete relaxation processes and, thereby, provide the information about the proper relaxation time scales [2]. Moreover, these functions can be applied to estimate quantitatively and simply the so-called memory effects in many particle system dynamics [2], the dynamical heterogeneity effects in particle movements [10] and the breakdown of system ergodicity [11].Historically, the formulation of fluctuation-dissipation theorem [12] and the Zwanzig-Mori's projection operator f...

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Section: Microscopic Dynamics At Wave Numbers K ≤ Kmmentioning

confidence: 96%

Relaxation Processes in Many Particle Systems -- Recurrence Relations Approach

Мокшин¹

2013

DNC

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“…Conversely, the spectral density of the TCF of the stress tensorS(ω) can be represented in the form [48]S…”

Section: ∂B(r) ∂Rmentioning

confidence: 99%

Viscosity of Cobalt Melt: Experiment, Simulation, and Theory

et al. 2018

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The results of experimental measurements, molecular dynamics simulation, and theoretical calculations of the viscosity of a cobalt melt in a temperature range of 1400 − 2000 K at a pressure p = 1.5 bar corresponding to an overcooled melt at temperatures of 1400 − 1768 K and an equilibrium melt with temperatures from the range 1768 − 2000 K are presented. Theoretical expressions for the spectral density of the time-dependent correlation function of the stress tensorS(ω) and kinematic viscosity ν determined from the frequency and thermodynamic parameters of the system are obtained. The temperature dependences of the kinematic viscosity for the cobalt melt are determined experimentally by the torsional oscillation method; numerically, based on molecular simulation data with the EAM potential via subsequent analysis of the time correlation functions of the transverse current in the framework of generalized hydrodynamics; and by the integral Kubo-Green relation;they were also determined theoretically with the Zwanzig-Mori memory functions formalism using a self-consistent approach. Good agreement was found between the results of theoretical calculations for the temperature dependence of the kinematic viscosity of the cobalt melt using experimental data and the molecular dynamics simulation results. From an analysis of the temperature dependence of the viscosity, we obtain an activation energy of E = (5.38 ± 0.02) × 10 −20 J.

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“…ρ is the number density, and g(r) is the pair radial distribution function. On the other hand, according to the formalism of the time correlation functions [34,39], the spectral density of TCF of the stress tensorS(ω) can be represented as infinite continuous fraction:…”

Section: Theoretical Formalismmentioning

confidence: 99%

Viscosity and structure configuration properties of equilibrium and supercooled liquid cobalt

Khusnutdinoff

Мокшин

Bel’tyukov

et al. 2018

Physics and Chemistry of Liquids

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The shear viscosity of liquid cobalt at the pressure p = 1.5 bar and at the temperatures corresponding to equilibrium liquid and supercooled liquid states is measured experimentally and evaluated by means of molecular dynamics simulations. Further, the shear viscosity is also calculated within the microscopic theoretical model. Comparison of our experimental, simulation and theoretical results with other available data allows one to examine the issue about the correct temperature dependence of the shear viscosity of liquid cobalt. It is found a strong correlation between the viscosity and the configuration entropy of liquid cobalt over the considered temperature range, which can be taken into account by the Rosenfeld's model.

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Collective dynamics in liquid aluminum near the melting temperature: Theory and computer simulation

Cited by 28 publications

References 29 publications

Relaxation Processes in Many Particle Systems -- Recurrence Relations Approach

Relaxation Processes in Many Particle Systems -- Recurrence Relations Approach

Viscosity of Cobalt Melt: Experiment, Simulation, and Theory

Viscosity and structure configuration properties of equilibrium and supercooled liquid cobalt

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