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## Microscopic mechanisms of diffusion of higher alkanes

Polymer Science - Series A. 2016. Vol. 58. No. 5. P. 825–836.

Translator: K. Aleksyan

With the use of n -triacontane models as examples, abnormal characteristics of diffusion that manifest themselves during the application of the Einstein–Smoluchowski relationship and the asymptotic behavior of velocity autocorrelation function of the molecule-mass centers that is used to calculate the diffusion coefficient via the Green–Kubo formula are investigated. On the basis of the data of complementary approaches, the microscopic mechanisms of diffusion in higher alkanes are outlined. The applicability of the Stokes–Einstein relationship for the viscosity coefficient is demonstrated.

Kondratyuk N., Norman G., Stegailov V., Высокомолекулярные соединения. Серия А 2016 Т. 58 № 5 С. 519–531

With the use of n-triacontane models as examples, abnormal characteristics of diffusion that manifest themselves during the application of the Einstein–Smoluchowski relationship and the asymptotic behavior of velocity autocorrelation function of the molecule-mass centers that is used to calculate the diffusion coefficient via the Green–Kubo formula are investigated. On the basis of the data of complementary ...

Added: April 7, 2017

Kondratyuk N., Norman G., Stegailov V., Journal of Chemical Physics 2016 Vol. 145 No. 204504 P. 204504-1–204504-9

iffusion is one of the key subjects of molecular modeling and simulation studies. However, there is an unresolved lack of consistency between Einstein-Smoluchowski (E-S) and Green-Kubo (G-K) methods for diffusion coefficient calculations in systems of complex molecules. In this paper, we analyze this problem for the case of liquid n-triacontane. The non-conventional long-time tails of the velocity autocorrelation function ...

Added: April 7, 2017

Kondratyuk N., Norman G., Stegailov V., Journal of Physics: Conference Series 2016 Vol. 774 No. 012039 P. 1–9

Molecular dynamics is applied to calculate diffusion coefficients of n-triacontane C30H62 using Einstein-Smoluchowski and Green-Kubo relations. The displacement 〈Δr2〉(t) has a subdiffusive part 〈Δr2〉 ~ t α, caused by molecular crowding at low temperatures. Longtime asymptotes of 〈v(0)v(t)〉 are collated with the hydrodynamic tail t-3/2 demonstrated for atomic liquids. The influence of these asymptotes on the compliance of Einstein-Smoluchowski ...

Added: April 7, 2017

Kondratyuk N., Lankin A., Norman G. et al., Journal of Physics: Conference Series 2015 Vol. 653 No. 012107 P. 1–9

Molecular modelling is used to calculate transport properties and to study relaxation of liquid n-triacontane (C30H62). The problem is important in connection with the behavior of liquid isolators in a pre-breakdown state. Two all-atom models and a united-atom model are used. Shear viscosity is calculated using the Green–Kubo formula. The force fields are compared with each other using the ...

Added: April 7, 2017

Kondratyuk N., Pisarev V., Ewen J., Journal of Chemical Physics 2020 Vol. 153 No. 15 P. 154502

Computational predictions of the high-pressure viscosity of hydrocarbon mixtures could help to accelerate the development of fuels and lubricants with improved performance. In this study, we use molecular dynamics simulations to study the viscosity and density of methylcyclohexane, 1-methylnaphthalene, and their binary mixtures at 323 K and pressures of up to 500 MPa. The simulation ...

Added: October 26, 2020

Gherardi M., Calabrese L., Tamm M. et al., Physical Review E - Statistical, Nonlinear, and Soft Matter Physics 2017 Vol. 96 No. 042402 P. 042402-1–042402-8

The short-time dynamics of bacterial chromosomal loci is a mixture of subdiffusive and active motion, in the form of rapid relocations with near-ballistic dynamics. While previous work has shown that such rapid motions are ubiquitous, we still have little grasp on their physical nature, and no positive model is available that describes them. Here, we ...

Added: December 22, 2017

Loganathan N., Bowers G. M., Ngouana-Wakou B. F. et al., Physical Chemistry Chemical Physics 2019 Vol. 21 P. 6917–6924

The interactions among fluid species such as H2O, CO2, and CH4 confined in nano- and meso-pores in shales and other rocks is of central concern to understanding the chemical behavior and transport properties of these species in the earthâ€™s subsurface and is of special concern to geological C-sequestration and enhanced production of oil and natural ...

Added: November 2, 2019

Kondratyuk N., Lenev D. Y., Pisarev V., Journal of Chemical Physics 2020 Vol. 152 No. 19 P. 191104

In this paper, the predictive power of molecular dynamics methods is demonstrated for the cases of model paraffinic and aromatic lubricant liquids at pressures up to 400 MPa. The shear viscosity and self-diffusion coefficients are calculated for 2,2,4-trimethylpentane (C8H18) at 298 K and 1,1-diphenylethane (C14H14) at 333 K. Three force fields with different levels of ...

Added: October 14, 2020

Valeev B. U., Pisarev V., Journal of Physics: Conference Series 2018 Vol. 946 P. 1–6

In this work, we study the vapor{liquid equilibrium in n-pentane. We use the TraPPE-EH (transferable potentials for phase equilibria - explicit hydrogen) forcefield, where each hydrogen and carbon atom is considered as independent center of force. The fluid behavior was investigated with different values of density and tempreture by molecular dynamics method. The n-pentane evaporation ...

Added: December 4, 2017

Bystryi R.G., Morozov I.V., Journal of Physics B: Atomic, Molecular and Optical Physics 2015 Vol. 48 No. 01-5401 P. 1–7

Irradiation of nanosized metallic clusters by femtosecond laser pulses of moderate intensities (10^12 – 10^14 W/cm^2) leads to creation of the so-called electron–ion nanoplasma with size-dependent properties. Electron oscillations in such plasma are of interest in view of resonance absorption or probing of cluster dynamics in experiments. We study the electronic oscillations via molecular dynamics ...

Added: December 25, 2014

Pouvreau M., Greathouse J. A., Cygan R. T. et al., Journal of Physical Chemistry C 2017 Vol. 121 No. 27 P. 14757–14771

Molecular scale understanding of the structure and properties of aqueous interfaces with clays, metal (oxy-) hydroxides, layered double hydroxides, and other inorganic phases is strongly affected by significant degrees of structural and compositional disorder of the interfaces. ClayFF was originally developed as a robust and flexible force field for classical molecular simulations of such systems ...

Added: July 13, 2017

Morozov I., Норман Г. Э., Журнал экспериментальной и теоретической физики 2005 Т. 127 № 2 С. 412–430

Плазменные волны и характер столкновений частиц в равновесной двухкомпонентной неидеальной плазме, состоящей из невырожденных электронов и однократно заряженных ионов, рассмотрены на основе моделирования методом молекулярной динамики (МД). Определены дисперсия частоты и декремента затухания ленгмюровских волн. Указан метод обобщения теории плазменных волн в идеальной плазме для расширения области применимости теории в сторону неидеальной плазмы. Определены проводимость ...

Added: March 14, 2014

Bodrova A., Соколов И. М., Physical Review E - Statistical, Nonlinear, and Soft Matter Physics 2020 Vol. 102 P. 032129

We consider Brownian motion under resetting in higher dimensions for the case when the return of the particle to the origin occurs at a constant speed. We investigate the behavior of the probability density function (PDF) and of the mean-squared displacement (MSD) in this process. We study two different resetting protocols: exponentially distributed time intervals ...

Added: September 20, 2020

Pisarev V., Mistry S., Fluid Phase Equilibria 2019 Vol. 484 P. 98–105

We present a study of viscosities of methane, n-butane and their mixtures by the non-equilibrium molecular dynamics simulations and derivation of semiempirical volume-based mixing rules. The Batchinski equation $\eta = C / (V - b)$ is used to describe the viscosities of pure components, with parameters fitted to reproduce molecular dynamics results. Cubic root, Arrhenius ...

Added: June 5, 2018

Быстрый Р.Г., Лавриненко Я. С., Ланкин А. В. et al., Теплофизика высоких температур 2014 Т. 52 № 4 С. 494–503

Pressure fluctuations in equilibrium nonideal plasma are investigated by the method of classical molecular dynamics. Examples of plasma parameters at which the pressure fluctuation distribution function is not normal but can be approximated by the sum of two normal distributions were found. The electron-ion interaction is described by the Coulomb potential cutoff at the depth ...

Added: December 25, 2014

Anna S. Bodrova, Physical Review E - Statistical, Nonlinear, and Soft Matter Physics 2024 Vol. 109 No. 2 Article 024903

We investigate diffusion in polydisperse granular media. We derive the mean-squared displacement of granular particles in a polydisperse granular gas in a homogeneous cooling state, containing an arbitrary amount of species of different sizes and masses. We investigate both models of constant and time-dependent restitution coefficients and obtain a universal law for the size dependence ...

Added: February 15, 2024

Pyrkova D. V., Tarasova N. K., Krylov N. et al., Journal of Biomolecular Structure and Dynamics 2013 Vol. 31 No. 1 P. 87–95

Delineation and analysis of lateral clustering of lipids in model bilayers is an important step toward understanding of the physical processes underlying formation of lipid domains and rafts in cell membranes. Computer modeling methods represent a powerful tool to address the problem since they can detect clusters of only few lipid molecules – this issue ...

Added: November 14, 2013

Kirova E. M., Norman G., Journal of Physics: Conference Series 2015 Vol. 653 P. 012106–012113

Viscosity and diffusion are chosen as an example to demonstrate the universality of diagnostics methods in the molecular dynamics method. To emphasize the universality, three diverse systems are investigated, which differ from each other drastically: liquids with embedded atom method and pairwise interatomic interaction potentials and dusty plasma with a unique multiparametric interparticle interaction potential. ...

Added: April 4, 2017

Timofeev A., Morozov I., Stegailov V. et al., Программные системы: теория и приложения 2014 Т. 5 № 1 С. 191–244

Рассматривается подход, позволяющий выявить, для каких задач нужны суперкомпьютеры эксафлопсного класса. Возможности подхода рассмотрены на примерах актуальных задач материаловедения, физики конденсированного вещества и плотной плазмы, для решения которых необходимо атомистическое моделирование на современных и создаваемых в настоящее время суперкомпьютерах. Для каждой задачи проведено соответствие между набором изучаемых явлений и требуемым уровнем быстродействия (числа ядер) вычислительной ...

Added: August 11, 2014

Efremov R., International Journal of Molecular Sciences 2021 Vol. 22 No. 12 P. 1–20

To date, it has been reliably shown that the lipid bilayer/water interface can be thoroughly characterized by a sophisticated so-called “dynamic molecular portrait”. The latter reflects a combination of time-dependent surface distributions of various physicochemical properties, inherent in both model lipid bilayers and natural multi-component cell membranes. One of the most important features of biomembranes ...

Added: August 24, 2021

Bodrova A., Sokolov I. M., Physical Review E - Statistical, Nonlinear, and Soft Matter Physics 2020 Vol. 101 No. 5 P. 052130

We consider a random two-phase process which we call a reset-return one. The particle starts
its motion at the origin. The rst, displacement, phase corresponds to a stochastic motion of a
particle and is nished at a resetting event. The second, return, phase corresponds to the particle's
motion towards the origin from the position it attained at the ...

Added: September 10, 2020

Артамонов А. В., Bondarenko G., Yakunkin M. M., Физика и химия обработки материалов 2008 № 1 С. 20–23

Исследовано влияние облучения системы B-Si электронами с энергией 8 МэВ на образование диффузионной зоны и тепловую проводимость границы раздела. Показано, что коэффициент диффузии бора в кремний при облучении при температуре 1200 K на порядок выше, чем без облучения, а величина тепловой проводимости близка к значению, характерному для идеального теплового контакта. ...

Added: January 4, 2013

Volynsky P., Efremov R., Mikhalev I. et al., Molecular Immunology 2017 Vol. 90 P. 87–97

Background
Human blood contains a big variety of natural antibodies, circulating throughout life at constant concentration. Previously, we have found natural antibodies capable of binding to trisaccharide Galα1-4Galβ1-4Glc (Pk) practically in all humans. Intriguingly, the same trisaccharide is a key fragment of glycosphingolipid globotriaosylceramide (Gb3Cer) – normal component of erythrocyte and endothelial cell membrane, i.e. the ...

Added: November 13, 2017

Orekhov N. D., Stegailov V., Carbon (the Netherlands) 2015 Vol. 87 P. 358–364

The graphite melting temperature remains poorly determined despite the considerable effort accomplished since the work of Bundy (1963). The absence of a consensus on its melting temperature at normal conditions has been considered as a technical problem that motivated more and more sophisticated experiments. The experimental evidences of the maximum on the graphite melting curve ...

Added: March 15, 2017