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Huang S, Voyles PM. Momentum transfer resolved electron correlation microscopy. Ultramicroscopy 2023; 256:113886. [PMID: 38000289 DOI: 10.1016/j.ultramic.2023.113886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 11/06/2023] [Accepted: 11/08/2023] [Indexed: 11/26/2023]
Abstract
Electron correlation microscopy (ECM) characterizes local structural relaxation dynamics in fluctuating systems like supercooled liquids with nanometer spatial resolution. We have developed a new type of ECM technique that provides moderate resolution in momentum transfer or k space using five-dimensional scanning transmission electron microscopy. k-resolved ECM on a Pt57.5Cu14.7Ni5.3P22.5 metallic supercooled liquids measures rich spatial and momentum structure in the relaxation time data τ(r,k). Relaxation time maps τ(r) at each azimuthal k are independent samples of the material's underlying relaxation time distribution, and τ of radial k shows more complex behavior than the de Gennes narrowing observed in analogous X-ray experiments. We have determined the requirements for electron counts per k-pixel, number of k-pixels per speckle, and time sampling to obtain reliable k-resolved ECM data.
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Affiliation(s)
- Shuoyuan Huang
- Department of Materials Science and Engineering, University of Wisconsin Madison, Madison, WI 53706, USA
| | - Paul M Voyles
- Department of Materials Science and Engineering, University of Wisconsin Madison, Madison, WI 53706, USA.
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2
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Shen Z, Carrillo JMY, Sumpter BG, Wang Y. Mesoscopic two-point collective dynamics of glass-forming liquids. J Chem Phys 2023; 159:114501. [PMID: 37712790 DOI: 10.1063/5.0161866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 08/24/2023] [Indexed: 09/16/2023] Open
Abstract
The collective density-density and hydrostatic pressure-pressure correlations of glass-forming liquids are spatiotemporally mapped out using molecular dynamics simulations. It is shown that the sharp rise of structural relaxation time below the Arrhenius temperature coincides with the emergence of slow, nonhydrodynamic collective dynamics on mesoscopic scales. The observed long-range, nonhydrodynamic mode is independent of wave numbers and closely coupled to the local structural dynamics. Below the Arrhenius temperature, it dominates the slow collective dynamics on length scales immediately beyond the first structural peak in contrast to the well-known behavior at high temperatures. These results highlight a key connection between the qualitative change in mesoscopic two-point collective dynamics and the dynamic crossover phenomenon.
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Affiliation(s)
- Zhiqiang Shen
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Jan-Michael Y Carrillo
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Bobby G Sumpter
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Yangyang Wang
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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3
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Arbe A, Nilsen GJ, Devonport M, Farago B, Alvarez F, Martínez González JA, Colmenero J. Collective dynamics and self-motions in the van der Waals liquid tetrahydrofuran from meso- to inter-molecular scales disentangled by neutron spectroscopy with polarization analysis. J Chem Phys 2023; 158:2889007. [PMID: 37154281 DOI: 10.1063/5.0147427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 04/18/2023] [Indexed: 05/10/2023] Open
Abstract
By using time-of-flight neutron spectroscopy with polarization analysis, we have separated coherent and incoherent contributions to the scattering of deuterated tetrahydrofuran in a wide scattering vector (Q)-range from meso- to inter-molecular length scales. The results are compared with those recently reported for water to address the influence of the nature of inter-molecular interactions (van der Waals vs hydrogen bond) on the dynamics. The phenomenology found is qualitatively similar in both systems. Both collective and self-scattering functions are satisfactorily described in terms of a convolution model that considers vibrations, diffusion, and a Q-independent mode. We observe a crossover in the structural relaxation from being dominated by the Q-independent mode at the mesoscale to being dominated by diffusion at inter-molecular length scales. The characteristic time of the Q-independent mode is the same for collective and self-motions and, contrary to water, faster and with a lower activation energy (≈1.4 Kcal/mol) than the structural relaxation time at inter-molecular length scales. This follows the macroscopic viscosity behavior. The collective diffusive time is well described by the de Gennes narrowing relation proposed for simple monoatomic liquids in a wide Q-range entering the intermediate length scales, in contraposition to the case of water.
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Affiliation(s)
- Arantxa Arbe
- Centro de Física de Materiales (CFM) (CSIC-UPV/EHU) - Materials Physics Center (MPC), Paseo Manuel de Lardizabal 5, 20018 San Sebastián, Spain
| | - Gøran J Nilsen
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom
| | - Mark Devonport
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom
| | - Bela Farago
- Institut Laue-Langevin, 71 avenue des Martyrs, Grenoble Cedex 9, 38042, France
| | - Fernando Alvarez
- Centro de Física de Materiales (CFM) (CSIC-UPV/EHU) - Materials Physics Center (MPC), Paseo Manuel de Lardizabal 5, 20018 San Sebastián, Spain
- Departamento de Polímeros y Materiales Avanzados: Física, Química y Tecnología (UPV/EHU), Apartado 1072, E-20080 San Sebastián, Spain
| | | | - Juan Colmenero
- Centro de Física de Materiales (CFM) (CSIC-UPV/EHU) - Materials Physics Center (MPC), Paseo Manuel de Lardizabal 5, 20018 San Sebastián, Spain
- Departamento de Polímeros y Materiales Avanzados: Física, Química y Tecnología (UPV/EHU), Apartado 1072, E-20080 San Sebastián, Spain
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 San Sebastián, Spain
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4
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Alvarez F, Arbe A, Colmenero J. Understanding the coherent dynamic structure factor of liquid water measured by neutron spectroscopy with polarization analysis: a Molecular Dynamics simulations study. EPJ WEB OF CONFERENCES 2022. [DOI: 10.1051/epjconf/202227201011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
This work is focused on atomistic molecular dynamics (MD) simulations of water carried out at 300 K. The main goal is to better understand the experimental results of the coherent dynamic structure factor S(Q,ν) of D2O that were obtained by means of neutron scattering with polarization analysis and previously reported by us [A. Arbe et al. Phys. Rev. Res. 2, 022015 (2020)]. From the simulations, we have calculated the coherent dynamic structure factor in the time domain S(Q,t) as well as its selfand distinctcontributions. We have also calculated S(Q,t) corresponding to a H2O sample. The main results obtained are: (i) The Q-independent relaxation process identified in S(Q,ν) in the mesoscopic range (Q0-mode) is the responsible of the restructuring of the hydrogen bond (HB) network at times shorter than that corresponding to the molecular diffusion; (ii) the vibrational contribution identified at high frequency in S(Q,ν) corresponds to a hydrodynamic-like mode propagating in an elastic medium (fixed HB bonding pattern); (iii) in the crossover range from mesoscopic to intermolecular scales, diffusion also progressively contributes to the decay of density fluctuations; (iv) MD-simulations suggest that it would be basically impossible to measure S(Q,ν,) of H2O in the mesoscopic range with the current neutron scattering capabilities.
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5
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Alvarez F, Arbe A, Colmenero J. Unraveling the coherent dynamic structure factor of liquid water at the mesoscale by molecular dynamics simulations. J Chem Phys 2021; 155:244509. [PMID: 34972354 DOI: 10.1063/5.0074588] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present an investigation by molecular dynamics (MD)-simulations of the coherent dynamic structure factor, S(Q, t) (Q: momentum transfer), of liquid water at the mesoscale (0.1 Å-1 ≤ Q ≤ Qmax) [Qmax ≈ 2 Å-1: Q-value of the first maximum of the static structure factor, S(Q), of water]. The simulation cell-large enough to address the collective properties at the mesoscale-is validated by direct comparison with recent results on the dynamic structure factor in the frequency domain obtained by neutron spectroscopy with polarization analysis [Arbe et al., Phys. Rev. Res. 2, 022015 (2020)]. We have not only focused on the acoustic excitations but also on the relaxational contributions to S(Q, t). The analysis of the MD-simulation results-including the self- and distinct contributions to the diffusive part of S(Q, t)-nicely explains why the relaxation process hardly depends on Q in the low Q-range (Q ≤ 0.4 Å-1) and how it crosses over to a diffusion-driven process at Q ≈ Qmax. Our simulations also give support to the main assumptions of the model used to fit the experimental data in the above mentioned paper. The application of such a model to the simulation S(Q, t) data delivers (i) results for the relaxation component of S(Q, t) in agreement with those obtained from neutron experiments and (ii) longitudinal and transverse hydrodynamic-like components with similar features than those identified in previous simulations of the longitudinal and transverse current spectra directly. On the other hand, in general, our MD-simulations results of S(Q, t) qualitatively agree with the viscoelastic transition framework habitually used to describe inelastic x-ray scattering results.
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Affiliation(s)
- Fernando Alvarez
- Centro de Física de Materiales (CSIC, UPV/EHU) and Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, E-20018 San Sebastián, Spain
| | - Arantxa Arbe
- Centro de Física de Materiales (CSIC, UPV/EHU) and Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, E-20018 San Sebastián, Spain
| | - Juan Colmenero
- Centro de Física de Materiales (CSIC, UPV/EHU) and Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, E-20018 San Sebastián, Spain
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Marín-Aguilar S, Smallenburg F, Sciortino F, Foffi G. Monodisperse patchy particle glass former. J Chem Phys 2021; 154:174501. [PMID: 34241071 DOI: 10.1063/5.0036963] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Glass formers are characterized by their ability to avoid crystallization. As monodisperse systems tend to rapidly crystallize, the most common glass formers in simulations are systems composed of mixtures of particles with different sizes. Here, we make use of the ability of patchy particles to change their local structure to propose them as monodisperse glass formers. We explore monodisperse systems with two patch geometries: a 12-patch geometry that enhances the formation of icosahedral clusters and an 8-patch geometry that does not appear to strongly favor any particular local structure. We show that both geometries avoid crystallization and present glassy features at low temperatures. However, the 8-patch geometry better preserves the structure of a simple liquid at a wide range of temperatures and packing fractions, making it a good candidate for a monodisperse glass former.
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Affiliation(s)
- Susana Marín-Aguilar
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, 91405 Orsay, France
| | - Frank Smallenburg
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, 91405 Orsay, France
| | - Francesco Sciortino
- Department of Physics, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy
| | - Giuseppe Foffi
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, 91405 Orsay, France
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7
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Soriano D, Zhou H, Hilke S, Pineda E, Ruta B, Wilde G. Relaxation dynamics of Pd-Ni-P metallic glass: decoupling of anelastic and viscous processes. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:164004. [PMID: 33725689 DOI: 10.1088/1361-648x/abef27] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 03/16/2021] [Indexed: 06/12/2023]
Abstract
The stress relaxation dynamics of metallic glass Pd40Ni40P20was studied in both supercooled liquid and glassy states. Time-temperature superposition was found in the metastable liquid, implying an invariant shape of the distribution of times involved in the relaxation. Once in the glass state, the distribution of relaxation times broadens as temperature and fictive temperature decrease, eventually leading to a decoupling of the relaxation in two processes. While the slow one keeps a viscous behavior, the fast one shows an anelastic nature and a time scale similar to that of the collective atomic motion measured by x-ray photon correlation spectroscopy (XPCS). These results suggest that the atomic dynamics of metallic glasses, as determined by XPCS at low temperatures in the glass state, can be related to the rearrangements of particles responsible of the macroscopically reversible anelastic behavior.
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Affiliation(s)
- Daniel Soriano
- Escola d'Enginyeria de Barcelona Est, Universitat Politècnica Catalunya-BarcelonaTech, 08019-Barcelona, Spain
| | - Hongbo Zhou
- Institute of Materials Physics, University of Muenster, Wilhelm-Klemm Strasse 10, 48149 Muenster, Germany
| | - Sven Hilke
- Institute of Materials Physics, University of Muenster, Wilhelm-Klemm Strasse 10, 48149 Muenster, Germany
| | - Eloi Pineda
- Departament de Física, Centre de Recerca en Ciència i Enginyeria Multiescala de Barcelona, Institut de Tècniques Energètiques, Universitat Politècnica de Catalunya-BarcelonaTech, 08019-Barcelona, Spain
| | - Beatrice Ruta
- Institut Lumière Matière, UMR5306, Université Claude Bernard Lyon 1-CNRS, 69622 Villeurbanne, France
| | - Gerhard Wilde
- Institute of Materials Physics, University of Muenster, Wilhelm-Klemm Strasse 10, 48149 Muenster, Germany
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Ruta B, Hechler S, Neuber N, Orsi D, Cristofolini L, Gross O, Bochtler B, Frey M, Kuball A, Riegler SS, Stolpe M, Evenson Z, Gutt C, Westermeier F, Busch R, Gallino I. Wave-Vector Dependence of the Dynamics in Supercooled Metallic Liquids. PHYSICAL REVIEW LETTERS 2020; 125:055701. [PMID: 32794848 DOI: 10.1103/physrevlett.125.055701] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 07/01/2020] [Indexed: 06/11/2023]
Abstract
We present a detailed investigation of the wave-vector dependence of collective atomic motion in Au_{49}Cu_{26.9}Si_{16.3}Ag_{5.5}Pd_{2.3} and Pd_{42.5}Cu_{27}Ni_{9.5}P_{21} supercooled liquids close to the glass transition temperature. Using x-ray photon correlation spectroscopy in a previously uncovered spatial range of only a few interatomic distances, we show that the microscopic structural relaxation process mimics the structure and presents a marked slowing down at the main average interparticle distance. This behavior is accompanied by dramatic changes in the shape of the intermediate scattering functions, which suggest the presence of large dynamical heterogeneities at length scales corresponding to a few particle diameters. A ballisticlike mechanism of particle motion seems to govern the structural relaxation of the two systems in the highly viscous phase, likely associated with hopping of caged particles in agreement with theoretical studies.
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Affiliation(s)
- B Ruta
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622 Villeurbanne, France
- ESRF-The European Synchrotron, CS40220, 38043 Grenoble, France
| | - S Hechler
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622 Villeurbanne, France
- Chair of Metallic Materials, Department of Materials Science and Engineering, Saarland University, Campus C6.3, 66123 Saarbrücken, Germany
| | - N Neuber
- Chair of Metallic Materials, Department of Materials Science and Engineering, Saarland University, Campus C6.3, 66123 Saarbrücken, Germany
| | - D Orsi
- Dipartimento di Scienze Matematiche Fisiche ed Informatiche, Università degli Studi di Parma, Parma, Italy
| | - L Cristofolini
- Dipartimento di Scienze Matematiche Fisiche ed Informatiche, Università degli Studi di Parma, Parma, Italy
| | - O Gross
- Chair of Metallic Materials, Department of Materials Science and Engineering, Saarland University, Campus C6.3, 66123 Saarbrücken, Germany
| | - B Bochtler
- Chair of Metallic Materials, Department of Materials Science and Engineering, Saarland University, Campus C6.3, 66123 Saarbrücken, Germany
| | - M Frey
- Chair of Metallic Materials, Department of Materials Science and Engineering, Saarland University, Campus C6.3, 66123 Saarbrücken, Germany
| | - A Kuball
- Chair of Metallic Materials, Department of Materials Science and Engineering, Saarland University, Campus C6.3, 66123 Saarbrücken, Germany
| | - S S Riegler
- Chair of Metallic Materials, Department of Materials Science and Engineering, Saarland University, Campus C6.3, 66123 Saarbrücken, Germany
| | - M Stolpe
- Chair of Metallic Materials, Department of Materials Science and Engineering, Saarland University, Campus C6.3, 66123 Saarbrücken, Germany
| | - Z Evenson
- Heinz Maier-Leibnitz Zentrum (MLZ) and Physik Department, Technische Universität München, Lichtenbergstrasse 1, 85748 Garching, Germany
| | - C Gutt
- Department Physik, Universität Siegen, D-57072 Siegen, Germany
| | - F Westermeier
- Deutsches Elektronen Synchrotron DESY, D-22607 Hamburg, Germany
| | - R Busch
- Chair of Metallic Materials, Department of Materials Science and Engineering, Saarland University, Campus C6.3, 66123 Saarbrücken, Germany
| | - I Gallino
- Chair of Metallic Materials, Department of Materials Science and Engineering, Saarland University, Campus C6.3, 66123 Saarbrücken, Germany
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Zaccone A. Relaxation and vibrational properties in metal alloys and other disordered systems. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:203001. [PMID: 31962298 DOI: 10.1088/1361-648x/ab6e41] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The relaxation dynamics and the vibrational spectra of amorphous solids, such as metal alloys, have been intensely investigated as well separated topics in the past. The aim of this review is to summarize recent results in both these areas in an attempt to establish, or unveil, deeper connections between the two phenomena of relaxation and vibration. Theoretical progress in the area of slow relaxation dynamics of liquid and glassy systems and in the area of vibrational spectra of glasses and liquids is reviewed. After laying down a generic modelling framework to connect vibration and relaxation, the physics of metal alloys is considered where the emergence of power-law exponents has been identified both in the vibrational density of states (VDOS) as well as in density correlations. Also, theoretical frameworks which connect the VDOS to the relaxation behaviour and mechanical viscoelastic response in metallic glasses are reviewed. The same generic interpretative framework is then applied to the case of molecular glass formers where the emergence of stretched-exponential relaxation in dielectric relaxation can be put in quantitative relation with the VDOS by means of memory-function approaches. Further connections between relaxation and vibration are provided by the study of phonon linewidths in liquids and glasses, where a natural starting point is given by hydrodynamic theories. Finally, an agenda of outstanding issues including the appearance of compressed exponential relaxation in the intermediate scattering function of experimental and simulated systems (metal alloys, colloidal gels, jammed packings) is presented in light of available (or yet to be developed) mathematical models, and compared to non-exponential behaviour measured with macroscopic means such as mechanical spectroscopy/rheology.
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Affiliation(s)
- Alessio Zaccone
- Department of Physics 'A. Pontremoli', University of Milan, via Celoria 16, 20133 Milano, Italy. Statistical Physics Group, Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, CB3 0AS Cambridge, United Kingdom. Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, CB30HE Cambridge, United Kingdom
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Giuntoli A, Puosi F, Leporini D, Starr FW, Douglas JF. Predictive relation for the α-relaxation time of a coarse-grained polymer melt under steady shear. SCIENCE ADVANCES 2020; 6:eaaz0777. [PMID: 32494635 PMCID: PMC7182423 DOI: 10.1126/sciadv.aaz0777] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 01/27/2020] [Indexed: 05/14/2023]
Abstract
We examine the influence of steady shear on structural relaxation in a simulated coarse-grained unentangled polymer melt over a wide range of temperature and shear rates. Shear is found to progressively suppress the α-relaxation process observed in the intermediate scattering function, leading ultimately to a purely inertially dominated β-relaxation at high shear rates, a trend similar to increasing temperature. On the basis of a scaling argument emphasizing dynamic heterogeneity in cooled liquids and its alteration under material deformation, we deduce and validate a parameter-free scaling relation for both the structural relaxation time τα from the intermediate scattering function and the "stretching exponent" β quantifying the extent of dynamic heterogeneity over the entire range of temperatures and shear rates that we can simulate.
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Affiliation(s)
- Andrea Giuntoli
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersbug, Maryland 20899, USA
- Department of Physics, Wesleyan University, Middletown, Connecticut 06459, USA
| | - Francesco Puosi
- Dipartimento di Fisica “Enrico Fermi,” Università di Pisa, Largo B.Pontecorvo 3, I-56127 Pisa, Italy
| | - Dino Leporini
- Dipartimento di Fisica “Enrico Fermi,” Università di Pisa, Largo B.Pontecorvo 3, I-56127 Pisa, Italy
- IPCF-CNR, UOS Pisa, Italy
| | - Francis W. Starr
- Department of Physics, Wesleyan University, Middletown, Connecticut 06459, USA
| | - Jack F. Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersbug, Maryland 20899, USA
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Role of hydrodynamics in liquid-liquid transition of a single-component substance. Proc Natl Acad Sci U S A 2020; 117:4471-4479. [PMID: 32051252 DOI: 10.1073/pnas.1911544117] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Liquid-liquid transition (LLT) is an unconventional transition between two liquid states in a single-component system. This phenomenon has recently attracted considerable attention not only because of its counterintuitive nature but also since it is crucial for our fundamental understanding of the liquid state. However, its physical understanding has remained elusive, particularly of the critical dynamics and phase-ordering kinetics. So far, the hydrodynamic degree of freedom, which is the most intrinsic kinetic feature of liquids, has been neglected in its theoretical description. Here we develop a Ginzburg-Landau-type kinetic theory of LLT taking it into account, based on a two-order parameter model. We examine slow critical fluctuations of the nonconserved order parameter coupled to the hydrodynamic degree of freedom in equilibrium. We also study the nonequilibrium process of LLT. We show both analytically and numerically that domain growth becomes faster (slower), depending upon the density decrease (increase) upon the transition, as a consequence of hydrodynamic flow induced by the density change. The coupling between nonconserved order parameter and hydrodynamic interaction results in anomalous domain growth in both nucleation-growth-type and spinodal-decomposition-type LLT. Our study highlights the characteristic features of hydrodynamic fluctuations and phase ordering during LLT under complex interplay among conserved and nonconserved order parameters and the hydrodynamic transport intrinsic to the liquid state.
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