1
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Bakulin I, Kondratyuk N, Lankin A, Norman G. Properties of aqueous 1,4-dioxane solution via molecular dynamics. J Chem Phys 2021; 155:154501. [PMID: 34686058 DOI: 10.1063/5.0059337] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Polyethers are promising compounds for the creation of electrochemical energy storage systems. The molecular dynamics method can facilitate the search of compounds that have the most potential. However, the application of this method requires verification of the force fields. We perform molecular dynamics calculations of the physical properties of the aqueous 1,4-dioxane solution (density, enthalpy of mixing, and viscosity) and compare them to the available experimental data. In addition, we confirm the idea that the solution structure depends on the dioxane molar fraction, proposed in the experiment of Takamuku et al. [J. Mol. Liq. 83(1-3), 163-177 (1999)]. The hydrogen bonds between dioxane and water are analyzed. The correlation between the excess viscosity and enthalpy of mixing is demonstrated.
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Affiliation(s)
- I Bakulin
- Moscow Institute of Physics and Technology (National Research University), 141700 Dolgoprudnyi, Russia
| | - N Kondratyuk
- Moscow Institute of Physics and Technology (National Research University), 141700 Dolgoprudnyi, Russia
| | - A Lankin
- Moscow Institute of Physics and Technology (National Research University), 141700 Dolgoprudnyi, Russia
| | - G Norman
- Moscow Institute of Physics and Technology (National Research University), 141700 Dolgoprudnyi, Russia
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2
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Kondratyuk N, Lenev D, Pisarev V. Transport coefficients of model lubricants up to 400 MPa from molecular dynamics. J Chem Phys 2020; 152:191104. [PMID: 33687262 DOI: 10.1063/5.0008907] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
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 accuracy are compared by the ability to predict the experimental data. The Stokes-Einstein correlation between viscosity and self-diffusion is demonstrated for both compounds.
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Affiliation(s)
- N Kondratyuk
- Joint Institute for High Temperatures Russian Academy of Sciences, Moscow, Russia
| | - D Lenev
- Joint Institute for High Temperatures Russian Academy of Sciences, Moscow, Russia
| | - V Pisarev
- Joint Institute for High Temperatures Russian Academy of Sciences, Moscow, Russia
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3
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Guarini E, Neumann M, Bellissima S, Colognesi D, Bafile U. Density dependence of the dynamical processes governing the velocity autocorrelation function of a quantum fluid. Phys Rev E 2020; 100:062111. [PMID: 31962502 DOI: 10.1103/physreve.100.062111] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Indexed: 11/07/2022]
Abstract
We present an exponential mode analysis of the dynamical processes determining the time behavior of the Kubo velocity autocorrelation function (KVAF) of fluid para-H_{2}, as obtained by ring polymer molecular dynamics simulations at various fluid densities. The mechanisms contributing to the decay of the KVAF are thoroughly characterized at a slightly supercritical temperature, in a density interval ranging from the critical point to the fluid-solid transition. We show that the quantum nature of the system does not influence the specific phenomena and decay channels through which a loss in velocity correlation takes place, since these are the same as found in classical fluids. Similarly, a dynamical crossover is observed with increasing density, signaling the onset of a transverse-like dynamics like in classical systems. We also investigate the effect of density on the processes contributing to the most relevant property of a quantum fluid, namely, the large values of the total and zero-point kinetic energy arising through the Heisenberg uncertainty principle.
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Affiliation(s)
- Eleonora Guarini
- Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino, Italy
| | - Martin Neumann
- Fakultät für Physik der Universität Wien, Strudlhofgasse 4, A-1090 Vienna, Austria
| | - Stefano Bellissima
- Consiglio Nazionale delle Ricerche, Istituto di Fisica Applicata "Nello Carrara", via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy
| | - Daniele Colognesi
- Consiglio Nazionale delle Ricerche, Istituto di Fisica Applicata "Nello Carrara", via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy
| | - Ubaldo Bafile
- Consiglio Nazionale delle Ricerche, Istituto di Fisica Applicata "Nello Carrara", via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy
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4
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Yoon TJ, Patel LA, Ju T, Vigil MJ, Findikoglu AT, Currier RP, Maerzke KA. Thermodynamics, dynamics, and structure of supercritical water at extreme conditions. Phys Chem Chem Phys 2020; 22:16051-16062. [DOI: 10.1039/d0cp02288h] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Molecular dynamics (MD) simulations to understand the thermodynamic, dynamic, and structural changes in supercritical water across the Frenkel line and the melting line have been performed.
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Affiliation(s)
| | | | - Taeho Ju
- Los Alamos National Laboratory
- Los Alamos
- USA
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5
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Losey J, Sadus RJ. Structural behavior of fluids from the vapor and liquid region to the supercritical phase. Phys Rev E 2019; 100:052132. [PMID: 31869944 DOI: 10.1103/physreve.100.052132] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Indexed: 06/10/2023]
Abstract
A metric (χ) is introduced to quantify the relative proportion of particles having a specified number of near neighbors that are characteristic of liquid-phase properties. It can be used as a simple alternative to other methods for the investigation of some aspects of percolation behavior. Values of χ are obtained from molecular-dynamics simulations spanning the heterogeneous vapor and liquid region and the supercritical phase of the Lennard-Jones fluid. The supercritical phase can be delineated into regions of different structural properties. At different isochoric subcritical conditions, the temperature versus χ behavior shows evidence of inflections, which are associated with the onset of transitions from the vapor and liquid region to the supercritical phase. The analysis suggests a phenomenological requirement for the critical point in terms of a near-equal proportion of near neighbors with gaslike and liquidlike characteristics.
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Affiliation(s)
- James Losey
- Centre for Computational Innovations, Swinburne University of Technology, PO Box 218, Hawthorn, VIC, 3122, Australia
| | - Richard J Sadus
- Centre for Computational Innovations, Swinburne University of Technology, PO Box 218, Hawthorn, VIC, 3122, Australia
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6
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Guarini E, Neumann M, Bafile U, Bellissima S, Colognesi D. Dynamical Origin of the Total and Zero-Point Kinetic Energy in a Quantum Fluid. PHYSICAL REVIEW LETTERS 2019; 123:135301. [PMID: 31697543 DOI: 10.1103/physrevlett.123.135301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Indexed: 06/10/2023]
Abstract
By applying an exponential mode analysis to ring polymer molecular dynamics simulations of dense fluid parahydrogen, we find that the dynamical processes establishing the time behavior of the Kubo velocity autocorrelation function display the same nature as those already observed in high-density classical fluids. This result permits us to demonstrate that the exponential mode decomposition is a unique tool to identify which dynamical processes lead to one of the most notable properties of quantum fluids: the large value of the mean kinetic energy per particle and the importance of the zero-temperature quantum effects in determining it.
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Affiliation(s)
- Eleonora Guarini
- Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino, Italy
| | - Martin Neumann
- Fakultät für Physik der Universität Wien, Strudlhofgasse 4, A-1090 Wien, Austria
| | - Ubaldo Bafile
- Consiglio Nazionale delle Ricerche, Istituto di Fisica Applicata "Nello Carrara," via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy
| | - Stefano Bellissima
- Consiglio Nazionale delle Ricerche, Istituto di Fisica Applicata "Nello Carrara," via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy
| | - Daniele Colognesi
- Consiglio Nazionale delle Ricerche, Istituto di Fisica Applicata "Nello Carrara," via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy
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7
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Bellissima S, Neumann M, Bafile U, Colognesi D, Barocchi F, Guarini E. Density and time scaling effects on the velocity autocorrelation function of quantum and classical dense fluid para-hydrogen. J Chem Phys 2019; 150:074502. [DOI: 10.1063/1.5085202] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Affiliation(s)
- S. Bellissima
- Consiglio Nazionale delle Ricerche, Istituto di Fisica Applicata “Nello Carrara,” via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy
| | - M. Neumann
- Fakultät für Physik der Universität Wien, Strudlhofgasse 4, A-1090 Wien, Austria
| | - U. Bafile
- Consiglio Nazionale delle Ricerche, Istituto di Fisica Applicata “Nello Carrara,” via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy
| | - D. Colognesi
- Consiglio Nazionale delle Ricerche, Istituto di Fisica Applicata “Nello Carrara,” via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy
| | - F. Barocchi
- Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino, Italy
| | - E. Guarini
- Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino, Italy
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8
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Ignatyuk VV, Mryglod IM, Bryk T. A simple closure procedure for the study of velocity autocorrelation functions in fluids as a "bridge" between different theoretical approaches. J Chem Phys 2018; 149:054101. [PMID: 30089378 DOI: 10.1063/1.5042772] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Velocity autocorrelation functions (VAFs) of the fluids are studied on short- and long-time scales within a unified approach. This approach is based on an effective summation of the infinite continued fraction at a reasonable assumption about convergence of relaxation times of the high order memory functions, which have a purely kinetic origin. The VAFs obtained within our method are compared with computer simulation data for the liquid Ne at different densities and the results, which follow from the Markovian approximation for the highest order kinetic kernels. It is shown that in all the thermodynamic points and at the chosen level of the hierarchy, our results agree much better with the molecular dynamic data than those of the Markovian approximation. The density dependence of the transition time, needed for the fluid to attain the hydrodynamic stage of evolution, is evaluated. The common and distinctive features of our method are discussed in their relations to the generalized collective mode theory, the mode coupling theory, and some other theoretical approaches.
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Affiliation(s)
- V V Ignatyuk
- Institute for Condensed Matter Physics, 1 Svientsitskii Street, 79011 Lviv, Ukraine
| | - I M Mryglod
- Institute for Condensed Matter Physics, 1 Svientsitskii Street, 79011 Lviv, Ukraine
| | - T Bryk
- Institute for Condensed Matter Physics, 1 Svientsitskii Street, 79011 Lviv, Ukraine
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9
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Kondratyuk ND, Norman GE, Stegailov VV. Microscopic mechanisms of diffusion of higher alkanes. POLYMER SCIENCE SERIES A 2018. [DOI: 10.1134/s0965545x16050072] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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10
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Anikeenko AV, Malenkov GG, Naberukhin YI. Visualization of the collective vortex-like motions in liquid argon and water: Molecular dynamics simulation. J Chem Phys 2018. [DOI: 10.1063/1.5018140] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Affiliation(s)
- A. V. Anikeenko
- Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia
- Novosibirsk State University, Novosibirsk 630090, Russia
| | - G. G. Malenkov
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow 115409, Russia
| | - Yu. I. Naberukhin
- Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia
- Novosibirsk State University, Novosibirsk 630090, Russia
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11
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Bellissima S, Neumann M, Guarini E, Bafile U, Barocchi F. Density of states and dynamical crossover in a dense fluid revealed by exponential mode analysis of the velocity autocorrelation function. Phys Rev E 2017; 95:012108. [PMID: 28208443 DOI: 10.1103/physreve.95.012108] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Indexed: 11/07/2022]
Abstract
Extending a preceding study of the velocity autocorrelation function (VAF) in a simulated Lennard-Jones fluid [Phys. Rev. E 92, 042166 (2015)PLEEE81539-375510.1103/PhysRevE.92.042166] to cover higher-density and lower-temperature states, we show that the recently demonstrated multiexponential expansion method allows for a full account and understanding of the basic dynamical processes encompassed by a fundamental quantity as the VAF. In particular, besides obtaining evidence of a persisting long-time tail, we assign specific and unambiguous physical meanings to groups of exponential modes related to the longitudinal and transverse collective dynamics, respectively. We have made this possible by consistently introducing the interpretation of the VAF frequency spectrum as a global density of states in fluids, generalizing a solid-state concept, and by giving to specific spectral components, obtained through the VAF exponential expansion, the corresponding meaning of partial densities of states relative to specific dynamical processes. The clear identification of a high-frequency oscillation of the VAF with the near-top excitation frequency in the dispersion curve of acoustic waves is a neat example of the power of the method. As for the transverse mode contribution, its analysis turns out to be particularly important, because the multiexponential expansion reveals a transition marking the onset of propagating excitations when the density is increased beyond a threshold value. While this finding agrees with the recent literature debating the issue of dynamical crossover boundaries, such as the one identified with the Frenkel line, we can add detailed information on the modes involved in this specific process in the domains of both time and frequency. This will help obtain a still missing full account of transverse dynamics, in both its nonpropagating and propagating aspects which are linked through dynamical transitions depending on both the thermodynamic states and the excitation wave vectors.
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Affiliation(s)
- S Bellissima
- Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino, Italy
| | - M Neumann
- Fakultät für Physik der Universität Wien, Strudlhofgasse 4, A-1090 Wien, Austria
| | - E Guarini
- Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino, Italy
| | - U Bafile
- Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy
| | - F Barocchi
- Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino, Italy
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12
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Peng HL, Schober HR, Voigtmann T. Velocity autocorrelation function in supercooled liquids: Long-time tails and anomalous shear-wave propagation. Phys Rev E 2016; 94:060601. [PMID: 28085468 DOI: 10.1103/physreve.94.060601] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Indexed: 06/06/2023]
Abstract
Molecular dynamic simulations are performed to reveal the long-time behavior of the velocity autocorrelation function (VAF) by utilizing the finite-size effect in a Lennard-Jones binary mixture. Whereas in normal liquids the classical positive t^{-3/2} long-time tail is observed, we find in supercooled liquids a negative tail. It is strongly influenced by the transfer of the transverse current wave across the period boundary. The t^{-5/2} decay of the negative long-time tail is confirmed in the spectrum of VAF. Modeling the long-time transverse current within a generalized Maxwell model, we reproduce the negative long-time tail of the VAF, but with a slower algebraic t^{-2} decay.
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Affiliation(s)
- H L Peng
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln, Germany
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - H R Schober
- Peter Grünberg Institut, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Th Voigtmann
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln, Germany
- Department of Physics, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany
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13
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Kondratyuk ND, Norman GE, Stegailov VV. Self-consistent molecular dynamics calculation of diffusion in higher n-alkanes. J Chem Phys 2016; 145:204504. [PMID: 27908129 DOI: 10.1063/1.4967873] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Diffusion 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 (VACF) are found for this system. Temperature dependence of the VACF tail decay exponent is defined. The proper inclusion of the long-time tail contributions to the diffusion coefficient calculation results in the consistency between G-K and E-S methods. Having considered the major factors influencing the precision of the diffusion rate calculations in comparison with experimental data (system size effects and force field parameters), we point to hydrogen nuclear quantum effects as, presumably, the last obstacle to fully consistent n-alkane description.
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Affiliation(s)
- Nikolay D Kondratyuk
- Joint Institute for High Temperatures of the Russian Academy of Sciences, Moscow 125412, Russia
| | - Genri E Norman
- Joint Institute for High Temperatures of the Russian Academy of Sciences, Moscow 125412, Russia
| | - Vladimir V Stegailov
- Joint Institute for High Temperatures of the Russian Academy of Sciences, Moscow 125412, Russia
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14
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Bellissima S, Neumann M, Guarini E, Bafile U, Barocchi F. Time dependence of the velocity autocorrelation function of a fluid: An eigenmode analysis of dynamical processes. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:042166. [PMID: 26565227 DOI: 10.1103/physreve.92.042166] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2015] [Indexed: 06/05/2023]
Abstract
The velocity autocorrelation function (VAF), a key quantity in the atomic-scale dynamics of fluids, has been the first paradigmatic example of a long-time tail phenomenon, and much work has been devoted to detecting such long-lasting correlations and understanding their nature. There is, however, much more to the VAF than simply the evidence of this long-time dynamics. A unified description of the VAF from very short to long times, and of the way it changes with varying density, is still missing. Here we show that an approach based on very general principles makes such a study possible and opens the way to a detailed quantitative characterization of the dynamical processes involved at all time scales. From the analysis of molecular dynamics simulations for a slightly supercritical Lennard-Jones fluid at various densities, we are able to evidence the presence of distinct fast and slow decay channels for the velocity correlation on the time scale set by the collision rate. The density evolution of these decay processes is also highlighted. The method presented here is very general, and its application to the VAF can be considered as an important example.
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Affiliation(s)
- S Bellissima
- Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino, Italy
| | - M Neumann
- Fakultät für Physik der Universität Wien, Strudlhofgasse 4, A-1090 Wien, Austria
| | - E Guarini
- Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino, Italy
| | - U Bafile
- Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy
| | - F Barocchi
- Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino, Italy
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15
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Ryltsev R, Klumov B, Chtchelkatchev N. Self-assembly of the decagonal quasicrystalline order in simple three-dimensional systems. SOFT MATTER 2015; 11:6991-6998. [PMID: 26234538 DOI: 10.1039/c5sm01397f] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Using molecular dynamics simulations we show that a one-component system can be driven to a three-dimensional decagonal (10-fold) quasicrystalline state just by purely repulsive, isotropic and monotonic interaction pair potential with two characteristic length scales; no attraction is needed. We found that self-assembly of a decagonal quasicrystal from a fluid can be predicted by two dimensionless effective parameters describing the fluid structure. We demonstrate stability of the results under changes of the potential by obtaining the decagonal order for three particle systems with different interaction potentials, both purely repulsive and attractive, but with the same values of the effective parameters. Our results suggest that soft matter quasicrystals with decagonal symmetry can be experimentally observed for the same systems demonstrating the dodecagonal order for an appropriate tuning of the effective parameters.
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Affiliation(s)
- Roman Ryltsev
- Institute of Metallurgy, UB RAS, 620016, Amundsena 101, Ekaterinburg, Russia.
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16
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Shvab I, Sadus RJ. Thermophysical properties of supercritical water and bond flexibility. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:012124. [PMID: 26274141 DOI: 10.1103/physreve.92.012124] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Indexed: 06/04/2023]
Abstract
Molecular dynamics results are reported for the thermodynamic properties of supercritical water using examples of both rigid (TIP4P/2005) and flexible (TIP4P/2005f) transferable interaction potentials. Data are reported for pressure, isochoric and isobaric heat capacities, the thermal expansion coefficient, isothermal and adiabatic compressibilities, Joule-Thomson coefficient, speed of sound, self-diffusion coefficient, viscosities, and thermal conductivity. Many of these properties have unusual behavior in the supercritical phase such as maximum and minimum values. The effectiveness of bond flexibility on predicting these properties is determined by comparing the results to experimental data. The influence of the intermolecular potential on these properties is both variable and state point dependent. In the vicinity of the critical density, the rigid and flexible potentials yield very different values for the compressibilities, heat capacities, and thermal expansion coefficient, whereas the self-diffusion coefficient, viscosities, and thermal conductivities are much less potential dependent. Although the introduction of bond flexibility is a computationally expedient way to improve the accuracy of an intermolecular potential, it can be counterproductive in some cases and it is not an adequate replacement for incorporating the effects of polarization.
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Affiliation(s)
- I Shvab
- School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom
| | - Richard J Sadus
- Centre for Molecular Simulation, Swinburne University of Technology, PO Box 218, Hawthorn, Victoria 3122, Australia
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