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受賞国：アメリカ合衆国

受賞国：フランス共和国

受賞国：アメリカ合衆国

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受賞国：グレートブリテン・北アイルランド連合王国(英国)

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受賞国：日本国

受賞国：日本国

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記述言語：英語  

DOI： 10.1063/5.0087578

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/acsomega.1c04960

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.1073/pnas.2118492119

担当区分：筆頭著者,　最終著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.1678/rheology.50.63

その他リンク： https://www.jstage.jst.go.jp/article/rheology/50/1/50_63/_article/-char/ja

記述言語：英語  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3389/fphy.2021.667103

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/d0sm00856g

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1126/sciadv.aba8766

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1103/PhysRevLett.124.225502

担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3389/fphy.2020.00099

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1103/PhysRevLett.124.058001

DOI： 10.1103/PhysRevLett.124.058001

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/C9SM01488H

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1063/1.5082154

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1063/1.5086379

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1088/1742-5468/ab3114

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1103/PhysRevE.98.012609

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ROYAL SOC CHEMISTRY  

We propose a new method to characterize the spatial distribution of particles' vibrations in solids with much lower computational costs compared to the usual normal mode analysis. We excite the specific vibrational mode in a two dimensional athermal jammed system by giving a small amplitude of active oscillation to each particle's size with an identical driving frequency. The response is then obtained as the real time displacements of the particles. We show remarkable correlations between the real time displacements and the eigen vectors obtained from conventional normal mode analysis. More importantly, from these real time displacements, we can measure the participation ratio and spatial polarization of particles' vibrations. From these measurements, we find three distinct frequency regimes which characterize the spatial distribution and correlation of particles' vibrations in jammed amorphous solids. Furthermore, we can possibly apply this method to a much larger system to examine the low frequency behaviour of amorphous solids with a much higher resolution of the frequency space.

DOI： 10.1039/c6sm00788k

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 8118

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1371/journal.pcbi.1006545

PubMed

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Institute of Physics Publishing  

It has recently been revealed that long-wavelength fluctuation exists in two-dimensional (2D) glassy systems, having the same origin as that given by the Mermin-Wagner theorem for 2D crystalline solids. In this paper, we discuss how to characterise quantitatively the long-wavelength fluctuation in a molecular dynamics simulation of a lightly supercooled liquid. We employ the cage-relative mean-square displacement (MSD), defined on relative displacement to its cage, to quantitatively separate the long-wavelength fluctuation from the original MSD. For increasing system size the amplitude of acoustic long wavelength fluctuations not only increases but shifts to later times causing a crossover with structural relaxation of caging particles. We further analyse the dynamic correlation length using the cage-relative quantities. It grows as the structural relaxation becomes slower with decreasing temperature, uncovering an overestimation by the four-point correlation function due to the long-wavelength fluctuation. These findings motivate the usage of cage-relative MSD as a starting point for analysis of 2D glassy dynamics.

DOI： 10.1088/1361-648X/aaa8b8

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

By using large-scale molecular dynamics simulations, the dynamics of two-dimensional (2D) supercooled liquids turns out to be dependent on the system size, while the size dependence is not pronounced in three-dimensional (3D) systems. It is demonstrated that the strong system-size effect in 2D amorphous systems originates from the enhanced fluctuations at long wavelengths which are similar to those of 2D crystal phonons. This observation is further supported by the frequency dependence of the vibrational density of states, consisting of the Debye approximation in the low-wave-number limit. However, the system-size effect in the intermediate scattering function becomes negligible when the length scale is larger than the vibrational amplitude. This suggests that the finite-size effect in a 2D system is transient and also that the structural relaxation itself is not fundamentally different from that in a 3D system. In fact, the dynamic correlation lengths estimated from the bond-breakage function, which do not suffer from those enhanced fluctuations, are not size dependent in either 2D or 3D systems.

DOI： 10.1103/PhysRevLett.117.245701

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

We use computer simulations to analyze the yielding transition during large-amplitude oscillatory shear of a simple model for soft jammed solids. Simultaneous analysis of global mechanical response and particle-scale motion demonstrates that macroscopic yielding, revealed by a smooth crossover in mechanical properties, is accompanied by a sudden change in the particle dynamics, which evolves from nondiffusive motion to irreversible diffusion as the amplitude of the shear is increased. We provide numerical evidence that this sharp change corresponds to a nonequilibrium first-order dynamic phase transition, thus establishing the existence of a well-defined microscopic dynamic signature of the yielding transition in amorphous materials in oscillatory shear.

DOI： 10.1103/PhysRevE.94.022615

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER ASSOC ADVANCEMENT SCIENCE  

The violation of the Stokes-Einstein (SE) relation D similar to (h/T)(-1) between the shear viscosity h and the translational diffusion constant D at temperature T is of great importance for characterizing anomalous dynamics of supercooled water. Determining which time scales play key roles in the SE violation remains elusive without the measurement of h. We provide comprehensive simulation results of the dynamic properties involving h and D in the TIP4P/2005 supercooled water. This enabled the thorough identification of the appropriate time scales for the SE relation Dh/T. In particular, it is demonstrated that the temperature dependence of various time scales associated with structural relaxation, hydrogen bond breakage, stress relaxation, and dynamic heterogeneities can be definitely classified into only two classes. That is, we propose the generalized SE relations that exhibit "violation" or "preservation." The classification depends on the examined time scales that are coupled or decoupled with the diffusion. On the basis of the classification, we explain the physical origins of the violation in terms of the increase in the plateau modulus and the nonexponentiality of stress relaxation. This implies that the mechanism of SE violation is attributed to the attained solidity upon supercooling, which is in accord with the growth of non-Gaussianity and spatially heterogeneous dynamics.

DOI： 10.1126/sciadv.1700399

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Physical Society (APS)  

DOI： 10.1103/physrevlett.123.265501

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その他リンク： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevLett.123.265501/fulltext

記述言語：英語  

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記述言語：英語  

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記述言語：英語  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

DOI： 10.1103/PhysRevE.95.069901

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記述言語：英語   出版者・発行元：AMER PHYSICAL SOC  

DOI： 10.1103/PhysRevLett.117.239902

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/c6sm90096h

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PubMed

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.1103/PhysRevE.91.012203

出版者・発行元：分子シミュレーション研究会  

DOI： 10.11436/mssj.17.181

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： doi:10.1209/0295-5075/107/28009

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： http://dx.doi.org/10.1103/PhysRevE.89.062315

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： http://dx.doi.org/10.1063/1.4873346

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： http://dx.doi.org/10.1063/1.4829442

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER INST PHYSICS  

Using molecular dynamics simulation on a glass-forming liquid in three dimensions, we investigate the thermal vibrational motions, the configuration changes caused by stringlike jump motions, and their close correlations. The heterogeneous vibrational motions are visualized in terms of a vibration length S-i(t) defined for each particle i. The structure factor for the inhomogeneity of S-i(t)(2) is also calculated, which exhibits considerable long wavelength enhancement. By examining the birth times of strings, they are shown to appear collectively and intermittently. We show that particles with larger S-i(t) tend to trigger jump motions more frequently at later times than those with smaller S-i(t). We also show that the particles with fewer bonds tend to have larger S-i(t) and participate more frequently in the stringlike motions. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4770337]

DOI： 10.1063/1.4770337

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： http://dx.doi.org/10.1103/PhysRevE.87.012312

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： http://dx.doi.org/10.1063/1.4770337

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

To understand the quantitative properties of dynamic heterogeneities on glassy particle systems, we use the theoretical scheme of bond-breakage which can detect configuration rearrangements corresponding to the structural relaxations. It is compared with the four-point correlation scheme for the results of binary mixtures with molecular dynamics simulations of two dimensional NVE ensembles. From the comparisons in the systems, we find superpositions of heterogeneity of configuration rearrangements and that induced by low-frequency vibration modes. The bond breakage scheme detects the long-time relaxations without short-time vibrations. The four-point scheme detects the mixed dynamics of the both. We find that the results on four-point scheme are sensitive to the influence of such vibration modes which gives rise to detectable system-size effects in physical properties. © 2013 American Institute of Physics.

DOI： 10.1063/1.4794679

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：AMER INST PHYSICS  

The origin of slow dynamics near glass transition and the mechanism of crystal nucleation are two unsolved fundamental problems associated with the metastable supercooled state of a liquid. So far these phenomena have been considered rather independently, however, we have revealed an intimate link between them. Recently we found that crystal-like bond orientational order develops in the supercooled state of (nearly) single-component systems such as spin liquids and weakly polydisperse colloidal liquids. In these liquids, low free-energy configurations in a supercooled liquid have a link to the rotational symmetry which is going to be broken upon crystallization. We argue that this is a direct consequence of that the same free energy governs both glass transition and crystallization at least in this type of liquids. We found that it is such structural ordering at least in this type of liquids that causes glassy slow dynamics and dynamic heterogeneity. Furthermore, we revealed that such structural order also plays a crucial role in crystal nucleation: Crystallization is a process of the enhancement of spatial coherence of crystal-like bond orientational order and 'not' driven by translational order at least in the nucleation stage. These results clearly indicate that the theoretical description at the two-body level is not enough to describe these phenomena and it is crucial to take into account many body correlations, particularly, bond orientational correlations. We argue that there is an intrinsic link between glass transition and crystallization if crystallization does not accompany other processes such as phase separation. If crystallization involves phase separation, on the other hand, such a direct link may be lost. We speculate that even in such a case glassy structural order may still be associated with low free-energy local configurations.

DOI： 10.1063/1.4794561

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： http://dx.doi.org/10.1103/PhysRevE.86.041504

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SOC RHEOLOGY, JAPAN  

We review our recent studies on the structural disorder in crystal, polycrystal, and glass in a Lennard-Jones binary mixture in three dimensions using molecular dynamics simulation. At a low temperature, the crossovers among these states occur as the amount of the large particles is varied. We define a disorder variable D-j (t) for each particle j in terms of local bond order parameters based on spherical harmonics (Steinhardt order parameters). Mesoscopic structural heterogeneity in glass is then visualized. In fcc crystal and polycrystal, we show that stacking faults play an important role in plasticity.

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： http://dx.doi.org/10.1063/1.3656762

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：NATURE PUBLISHING GROUP  

Spatial confinement is known to induce a drastic change in the viscosity, relaxation times, and flow profile of liquids near the glass (or jamming) transition point. The essential underlying question is how a wall affects the dynamics of densely packed systems. Here we study this fundamental problem, using experiments on a driven granular hard-sphere liquid and numerical simulations of polydisperse and bidisperse colloidal liquids. The nearly hard-core nature of the particle-wall interaction provides an ideal opportunity to study purely geometrical confinement effects. We reveal that the slower dynamics near a wall is induced by wall-induced enhancement of `glassy structural order', which is a manifestation of strong interparticle correlations. By generalizing the structure-dynamics relation for bulk systems, we find a quantitative relation between the structural relaxation time at a certain distance from a wall and the correlation length of glassy structural order there. Our finding suggests that glassy structural ordering may be the origin of the slow glassy dynamics of a supercooled liquid.

DOI： 10.1038/NMAT3034

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： doi:10.1088/0953-8984/23/19/194121

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： doi:10.1038/nmat3034

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： doi: 10.1073/pnas.1001040107

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： doi:10.1088/0953-8984/22/23/232102

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： doi:10.1038/nmat2634

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： http://dx.doi.org/10.1103/PhysRevLett.102.185701

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： http://dx.doi.org/10.1103/PhysRevLett.100.099602

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：AMER INST PHYSICS  

Glasses are formed if crystallization is avoided upon cooling or increasing density. However, the physical factors controlling the ease of vitrification and nature of the glass transition remain elusive. We use numerical simulations of polydisperse hard disks to tackle both of these longstanding questions. Here we systematically control the polydispersity in two-dimensional colloidal simulations, i.e., the strength of frustration effects on crystallization. We demonstrate that medium-range crystalline order grows in size and lifetime with an increase in the colloid volume fraction or a decrease in polydispersity (or, frustration). We find a direct relation between medium-range crystalline ordering and the slow dynamics that characterizes the glass transition. This suggests an intriguing scenario that the strength of frustration controls both the ease of vitrification and nature of the glass transition at least in this system. Vitrification may be a process of hidden crystalline ordering under frustration. This not only provides a physical basis for glass formation, but also an answer to a longstanding question on the structure of amorphous materials: "order in disorder" may be an intrinsic feature of a glassy state of material. Thus our scenario makes a natural connection between structure and dynamics in glass-forming materials, although its relevance should be carefully checked for 3D glass-forming liquids.

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： http://dx.doi.org/10.1103/PhysRevLett.99.215701

開催年月日： 2023年8月

記述言語：日本語   会議種別：シンポジウム・ワークショップ パネル（指名）  

開催地：マキノパークホテル   国名：日本国  

開催年月日： 2023年8月

開催地：Univ Tokyo, Tokyo   国名：日本国  

開催年月日： 2023年3月

記述言語：日本語   会議種別：口頭発表（招待・特別）  

開催地：オンライン   国名：日本国  

開催年月日： 2023年10月

記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：National Taiwan University, Taipei, Taiwan   国名：台湾  

Glass transitions are widely observed in various types of soft matter systems. However, the
physical mechanism of these transitions remains elusive despite years of ambitious research.
In particular, an important unanswered question is whether the glass transition is accompanied
by a divergence of the correlation lengths of the characteristic static structures. In this study,
we develop a deep-neural-network-based method that is used to extract the characteristic local
meso-structures solely from instantaneous particle configurations without any information
about the dynamics. We first train a neural network to classify configurations of liquids and
glasses correctly. Then, we obtain the characteristic structures by quantifying the grounds for
the decisions made by the network using Gradient-weighted Class Activation Mapping (Grad-
CAM). We consider two qualitatively different glass-forming binary systems, and through
comparisons with several established structural indicators, we demonstrate that our system
can be used to identify characteristic structures that depend on the details of the systems.
Moreover, the extracted structures are remarkably correlated with dynamics in thermal
fluctuations [1].
Reference:
[1] N. Oyama, S. Koyama, and T. Kawasaki, What Do Deep Neural Networks Find in
Disordered Structures of Glasses?, Frontiers in Physics 10:1007861 (2023).

開催年月日： 2023年8月

記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：Makuhari Messe,Chiba   国名：日本国  

開催年月日： 2023年3月

国名：日本国  

記述言語：日本語  

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記述言語：日本語  

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記述言語：日本語  

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記述言語：日本語   会議種別：口頭発表（一般）  

開催地：同志社大学  

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記述言語：日本語   会議種別：口頭発表（一般）  

開催地：筑波 産総研  

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記述言語：英語  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

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記述言語：英語   会議種別：口頭発表（一般）  

開催地：Kyoto  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：Nagoya  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：Fukuoka  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：京都大学  

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記述言語：日本語  

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記述言語：日本語   会議種別：口頭発表（基調）  

開催地：奈良先端科学技術大学院大学  

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記述言語：英語   会議種別：口頭発表（一般）  

開催地：Kyoto, Japan  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：Nara, Japan  

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記述言語：英語  

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記述言語：英語   会議種別：口頭発表（一般）  

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記述言語：英語   会議種別：口頭発表（一般）  

開催地：Bristol, UK  

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記述言語：英語   会議種別：口頭発表（一般）  

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記述言語：英語   会議種別：口頭発表（一般）  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

国名：マレーシア  

記述言語：日本語   会議種別：口頭発表（招待・特別）  

開催地：那覇（オンラインハイブリット）   国名：日本国  

記述言語：日本語   会議種別：口頭発表（招待・特別）  

開催地：名古屋大学   国名：日本国  

記述言語：日本語   会議種別：口頭発表（招待・特別）  

開催地：名古屋大学   国名：日本国  

記述言語：日本語   会議種別：口頭発表（招待・特別）  

開催地：九州大学   国名：日本国  

記述言語：日本語   会議種別：口頭発表（招待・特別）  

開催地：オンライン   国名：日本国  

記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：京都   国名：日本国  

対象： 大学生

種別：施設一般公開

対象： 大学生

種別：施設一般公開

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