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Li X, Jin Y. Thermodynamic crossovers in supercritical fluids. Proc Natl Acad Sci U S A 2024; 121:e2400313121. [PMID: 38652745 PMCID: PMC11067041 DOI: 10.1073/pnas.2400313121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Accepted: 03/26/2024] [Indexed: 04/25/2024] Open
Abstract
Can liquid-like and gas-like states be distinguished beyond the critical point, where the liquid-gas phase transition no longer exists and conventionally only a single supercritical fluid phase is defined? Recent experiments and simulations report strong evidence of dynamical crossovers above the critical temperature and pressure. Despite using different criteria, many existing theoretical explanations consider a single crossover line separating liquid-like and gas-like states in the supercritical fluid phase. We argue that such a single-line scenario is inconsistent with the supercritical behavior of the Ising model, which has two crossover lines due to its symmetry, violating the universality principle of critical phenomena. To reconcile the inconsistency, we define two thermodynamic crossover lines in supercritical fluids as boundaries of liquid-like, indistinguishable, and gas-like states. Near the critical point, the two crossover lines follow critical scalings with exponents of the Ising universality class, supported by calculations of theoretical models and analyses of experimental data from the standard database. The upper line agrees with crossovers independently estimated from the inelastic X-ray scattering data of supercritical argon, and from the small-angle neutron scattering data of supercritical carbon dioxide. The lower line is verified by the equation of states for the compressibility factor. This work provides a fundamental framework for understanding supercritical physics in general phase transitions.
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Affiliation(s)
- Xinyang Li
- Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing100049, China
| | - Yuliang Jin
- Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing100049, China
- Center for Theoretical Interdisciplinary Sciences, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang325001, China
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Cockrell C, Brazhkin VV, Trachenko K. Universal interrelation between dynamics and thermodynamics and a dynamically driven "c" transition in fluids. Phys Rev E 2021; 104:034108. [PMID: 34654136 DOI: 10.1103/physreve.104.034108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 08/26/2021] [Indexed: 06/13/2023]
Abstract
Our very wide survey of the supercritical phase diagram and its key properties reveals a universal interrelation between dynamics and thermodynamics and an unambiguous transition between liquidlike and gaslike states. This is seen in the master plot showing a collapse of the data representing the dependence of specific heat on key dynamical parameters in the system for many different paths on the phase diagram. As a result, the observed transition is path independent. We call it a "c" transition due to the c-shaped curve parametrizing the dependence of the specific heat on key dynamical parameters. The c transition has a fixed inversion point and provides a new structure to the phase diagram, operating deep in the supercritical state (up to, at least, 2000 times the critical pressure and 50 times the critical temperature). The data collapse and path independence as well as the existence of a special inversion point on the phase diagram are indicative of either of a sharp crossover or a new phase transition in the deeply supercritical state.
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Affiliation(s)
- C Cockrell
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, United Kingdom
| | - V V Brazhkin
- Institute for High Pressure Physics, RAS, 108840 Troitsk, Moscow, Russia
| | - K Trachenko
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, United Kingdom
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Kryuchkov NP, Yurchenko SO. Collective excitations in active fluids: Microflows and breakdown in spectral equipartition of kinetic energy. J Chem Phys 2021; 155:024902. [PMID: 34266286 DOI: 10.1063/5.0054854] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The effect of particle activity on collective excitations in active fluids of microflyers is studied. With an in silico study, we observed an oscillating breakdown of equipartition (uniform spectral distribution) of kinetic energy in reciprocal space. The phenomenon is related to short-range velocity-velocity correlations that were realized without forming of long-lived mesoscale vortices in the system. This stands in contrast to well-known mesoscale turbulence operating in active nematic systems (bacterial or artificial) and reveals the features of collective dynamics in active fluids, which should be important for structural transitions and glassy dynamics in active matter.
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Affiliation(s)
- Nikita P Kryuchkov
- Bauman Moscow State Technical University, 2nd Baumanskaya str. 5, 105005 Moscow, Russia
| | - Stanislav O Yurchenko
- Bauman Moscow State Technical University, 2nd Baumanskaya str. 5, 105005 Moscow, Russia
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4
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Abstract
An analytical derivation of the vibrational density of states (DOS) of liquids, and, in particular, of its characteristic linear in frequency low-energy regime, has always been elusive because of the presence of an infinite set of purely imaginary modes—the instantaneous normal modes (INMs). By combining an analytic continuation of the Plemelj identity to the complex plane with the overdamped dynamics of the INMs, we derive a closed-form analytic expression for the low-frequency DOS of liquids. The obtained result explains, from first principles, the widely observed linear in frequency term of the DOS in liquids, whose slope appears to increase with the average lifetime of the INMs. The analytic results are robustly confirmed by fitting simulations data for Lennard-Jones liquids, and they also recover the Arrhenius law for the average relaxation time of the INMs, as expected.
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Yue L, Zhang L, Lv L, Yang M. Phase separation in the supercritical mixtures of N2, H2O and CO2 through a molecular dynamics study. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.113811] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Kryuchkov NP, Mistryukova LA, Sapelkin AV, Brazhkin VV, Yurchenko SO. Universal Effect of Excitation Dispersion on the Heat Capacity and Gapped States in Fluids. PHYSICAL REVIEW LETTERS 2020; 125:125501. [PMID: 33016757 DOI: 10.1103/physrevlett.125.125501] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 07/17/2020] [Accepted: 07/23/2020] [Indexed: 06/11/2023]
Abstract
The change in dispersion of high-frequency excitations in fluids, from an oscillating solidlike to a monotonic gaslike one, is shown for the first time to affect thermal behavior of heat capacity and the q-gap width in reciprocal space. With in silico study of liquified noble gases, liquid iron, liquid mercury, and model fluids, we established universal bilinear dependence of heat capacity on q-gap width, whereas the crossover precisely corresponds to the change in the excitation spectra. The results open novel prospects for studies of various fluids, from simple to molecular liquids and melts.
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Affiliation(s)
- Nikita P Kryuchkov
- Bauman Moscow State Technical University, 2nd Baumanskaya street 5, Moscow 105005, Russia
| | - Lukiya A Mistryukova
- Bauman Moscow State Technical University, 2nd Baumanskaya street 5, Moscow 105005, Russia
| | - Andrei V Sapelkin
- School of Physics and Astronomy, Queen Mary University of London, London E1 4NS, England
| | - Vadim V Brazhkin
- Institute for High Pressure Physics RAS, Kaluzhskoe shosse, 14, Troitsk, Moscow 108840, Russia
| | - Stanislav O Yurchenko
- Bauman Moscow State Technical University, 2nd Baumanskaya street 5, Moscow 105005, Russia
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Kryuchkov NP, Mistryukova LA, Brazhkin VV, Yurchenko SO. Excitation spectra in fluids: How to analyze them properly. Sci Rep 2019; 9:10483. [PMID: 31324848 PMCID: PMC6642218 DOI: 10.1038/s41598-019-46979-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 07/09/2019] [Indexed: 11/25/2022] Open
Abstract
Although the understanding of excitation spectra in fluids is of great importance, it is still unclear how different methods of spectral analysis agree with each other and which of them is suitable in a wide range of parameters. Here, we show that the problem can be solved using a two-oscillator model to analyze total velocity current spectra, while other considered methods, including analysis of the spectral maxima and single mode analysis, yield rough results and become unsuitable at high temperatures and wavenumbers. To prove this, we perform molecular dynamics (MD) simulations and calculate excitation spectra in Lennard-Jones and inverse-power-law fluids at different temperatures, both in 3D and 2D cases. Then, we analyze relations between thermodynamic and dynamic features of fluids at (Frenkel) crossover from a liquid- to gas-like state and find that they agree with each other in the 3D case and strongly disagree in 2D systems due to enhanced anharmonicity effects. The results provide a significant advance in methods for detail analysis of collective fluid dynamics spanning fields from soft condensed matter to strongly coupled plasmas.
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Affiliation(s)
- Nikita P Kryuchkov
- Bauman Moscow State Technical University, 2nd Baumanskaya street 5, Moscow, 105005, Russia
| | - Lukiya A Mistryukova
- Bauman Moscow State Technical University, 2nd Baumanskaya street 5, Moscow, 105005, Russia
| | - Vadim V Brazhkin
- Institute for High Pressure Physics RAS, Kaluzhskoe shosse, 14, Troitsk, Moscow, 108840, Russia
| | - Stanislav O Yurchenko
- Bauman Moscow State Technical University, 2nd Baumanskaya street 5, Moscow, 105005, Russia.
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Wang L, Yang C, Dove MT, Mokshin AV, Brazhkin VV, Trachenko K. The nature of collective excitations and their crossover at extreme supercritical conditions. Sci Rep 2019; 9:755. [PMID: 30679686 PMCID: PMC6346117 DOI: 10.1038/s41598-018-36178-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 11/14/2018] [Indexed: 11/09/2022] Open
Abstract
Physical properties of an interacting system are governed by collective excitations, but their nature at extreme supercritical conditions is unknown. Here, we present direct evidence for propagating solid-like longitudinal phonon-like excitations with wavelengths extending to interatomic separations deep in the supercritical state at temperatures up to 3,300 times the critical temperature. We observe that the crossover of dispersion curves develops at k points reducing with temperature. We interpret this effect as the crossover from the collective phonon to the collisional mean-free path regime of particle dynamics and find that the crossover points are close to both the inverse of the shortest available wavelength in the system and to the particle mean free path inferred from experiments and theory. Notably, both the shortest wavelength and mean free path scale with temperature with the same power law, lending further support to our findings.
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Affiliation(s)
- L Wang
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
| | - C Yang
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.,Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - M T Dove
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - A V Mokshin
- Landau Institute for Theoretical Physics, Russian Academy of Sciences, 142432, Chernogolovka, Russia.,Institute of Physics, Kazan Federal University, 420008, Kazan, Russia
| | - V V Brazhkin
- Institute for High Pressure Physics, RAS, 108840, Moscow, Russia
| | - K Trachenko
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
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Takemoto A, Kinugawa K. Quantumness and state boundaries hidden in supercritical helium-4: A path integral centroid molecular dynamics study. J Chem Phys 2018; 149:204504. [DOI: 10.1063/1.5053988] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Ayumi Takemoto
- Division of Chemistry, Graduate School of Humanities and Sciences, Nara Women’s University, Nara 630-8506, Japan
| | - Kenichi Kinugawa
- Division of Chemistry, Graduate School of Humanities and Sciences, Nara Women’s University, Nara 630-8506, Japan
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Yoon TJ, Ha MY, Lazar EA, Lee WB, Lee YW. Topological Characterization of Rigid-Nonrigid Transition across the Frenkel Line. J Phys Chem Lett 2018; 9:6524-6528. [PMID: 30293429 DOI: 10.1021/acs.jpclett.8b02715] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The dynamics of supercritical fluids, a state of matter beyond the gas-liquid critical point, changes from diffusive to oscillatory motions at high pressure. This transition is believed to occur across a locus of thermodynamic states called the Frenkel line. The Frenkel line has been extensively investigated from the viewpoint of the dynamics, but its structural meaning is still not well-understood. This Letter interprets the mesoscopic picture of the Frenkel line entirely based on a topological and geometrical framework. This discovery makes it possible to understand the mechanism of rigid-nonrigid transition based not on the dynamics of individual atoms but on their instantaneous configurations. The topological classification method reveals that the percolation of solid-like structures occurs above the rigid-nonrigid crossover densities.
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Affiliation(s)
- Tae Jun Yoon
- School of Chemical and Biological Engineering, Institute of Chemical Processes , Seoul National University , Seoul 08826 , Republic of Korea
| | - Min Young Ha
- School of Chemical and Biological Engineering, Institute of Chemical Processes , Seoul National University , Seoul 08826 , Republic of Korea
| | - Emanuel A Lazar
- Materials Science and Engineering , University of Pennsylvania , Philadelphia , Pennsylvania 19104 , United States
| | - Won Bo Lee
- School of Chemical and Biological Engineering, Institute of Chemical Processes , Seoul National University , Seoul 08826 , Republic of Korea
| | - Youn-Woo Lee
- School of Chemical and Biological Engineering, Institute of Chemical Processes , Seoul National University , Seoul 08826 , Republic of Korea
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Abstract
The Frenkel line, a crossover line between rigid and nonrigid dynamics of fluid particles, has recently been the subject of intense debate regarding its relevance as a partitioning line of the supercritical phase, where the main criticism comes from the theoretical treatment of collective particle dynamics. From an independent point of view, this Letter suggests that the two-phase thermodynamics model may alleviate this contentious situation. The model offers new criteria for defining the Frenkel line in the supercritical region and builds a robust connection among the preexisting, seemingly inconsistent definitions. In addition, one of the dynamic criteria locates the rigid-nonrigid transition of the soft-sphere and the hard-sphere models. Hence, we suggest the Frenkel line be considered as a dynamic rigid-nonrigid fluid boundary, without any relation to gas-liquid transition. These findings provide an integrative viewpoint combining fragmentized definitions of the Frenkel line, allowing future studies to be carried out in a more reliable manner.
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Affiliation(s)
- Tae Jun Yoon
- School of Chemical and Biological Engineering, Institute of Chemical Processes , Seoul National University , Seoul 08826 , Republic of Korea
| | - Min Young Ha
- School of Chemical and Biological Engineering, Institute of Chemical Processes , Seoul National University , Seoul 08826 , Republic of Korea
| | - Won Bo Lee
- School of Chemical and Biological Engineering, Institute of Chemical Processes , Seoul National University , Seoul 08826 , Republic of Korea
| | - Youn-Woo Lee
- School of Chemical and Biological Engineering, Institute of Chemical Processes , Seoul National University , Seoul 08826 , Republic of Korea
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Schienbein P, Marx D. Investigation concerning the uniqueness of separatrix lines separating liquidlike from gaslike regimes deep in the supercritical phase of water with a focus on Widom line concepts. Phys Rev E 2018; 98:022104. [PMID: 30253513 DOI: 10.1103/physreve.98.022104] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Indexed: 06/08/2023]
Abstract
The supercritical phase of fluids has long been known to feature significantly different liquidlike and gaslike regimes. However, it is textbook knowledge that the supercritical state is a homogeneous fluid phase where properties change continuously. Nevertheless, there has been an increasing amount of evidence published that suggests that there might exist a unique line that rigorously separates different regimes in supercritical phases, particularly in the case of water. Here, we use the quasiexact IAPWS95 equation of state to rigorously assess the macroscopic thermodynamic properties of supercritical water without invoking any water model or related approximations. We focus on how these properties change deep in the supercritical phase, in particular if they allow one to introduce a unique "thermodynamic separatrix." Our rigorous thermodynamic analysis, which relies exclusively on accurate experimental data, makes clear that there is no unique separatrix in real supercritical water-such as the recently much-invoked "Widom line." A comparison to the van der Waals equation of state reproduces qualitatively all our findings for real water, thereby suggesting that our analysis should be transferable to other fluids and critical points. Topological analysis of the H-bond network structure of supercritical water, as obtained from molecular-dynamics simulations using a standard water model, demonstrates that also the percolation line does not provide a meaningful separatrix to rigorously distinguish liquidlike from gaslike regimes.
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Affiliation(s)
- Philipp Schienbein
- Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Dominik Marx
- Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, 44780 Bochum, Germany
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