Article
Physics, Multidisciplinary
Sangwoo Kim, Sascha Hilgenfeldt
Summary: This article investigates the metastable states in two-dimensional particle packings and classifies their energies using simple scalar measures of local steric packing. The study finds that these metastable states are insensitive to the particle interaction potential and can be used to efficiently guide a modified swap algorithm that quickly anneals packings towards low-energy metastable states. The approach also identifies ultrastable packings.
PHYSICAL REVIEW LETTERS
(2022)
Review
Physics, Multidisciplinary
Vladimir N. Novikov, Alexei P. Sokolov
Summary: This review focuses on the mechanisms that control the steepness of the temperature dependence of structural relaxation in glass-forming liquids. It discusses the specific case of polymeric glass-forming liquids and the possible role of quantum effects in the glass transition.
Article
Chemistry, Multidisciplinary
Darkhan Yerezhep, Aigerim Akylbayeva, Oleg Golikov, Dmitriy Yurievich Sokolov, Ainura Shinbayeva, Abdurakhman U. Aldiyarov
Summary: This study investigates the structural phase transitions in thin films of R134A using Fourier-transform infrared spectroscopy. Multiple structural phase states, including glassy forms, were observed. The shifts in absorption band peaks at frequencies of 842 cm(-1), 965 cm(-1), and 958 cm(-1), as well as at frequencies of 1055 cm(-1), 1170 cm(-1), and 1280 cm(-1), between temperatures of 80 K and 84 K indicate structural phase transformations in the samples.
Article
Chemistry, Physical
Xiao Jiang, Zean Tian, Kenli Li, Wangyu Hu
Summary: This paper addresses the challenge of modeling the dynamics of glassy systems and introduces a novel dynamic parameter called smoothness based on graph signal processing theory. The proposed Geometry-enhanced Graph Neural Network (Geo-GNN) is able to learn the smoothness of dynamics and outperforms existing baselines in predicting glassy dynamics.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Multidisciplinary Sciences
Walter Schirmacher, Taras Bryk, Giancarlo Ruocco
Summary: This study investigates the instantaneous normal mode spectrum of a simulated soft-sphere liquid at different equilibrium temperatures. The findings reveal a sharp maximum near (but not at) lambda = 0 in the spectrum of eigenvalues rho(lambda), which decreases monotonically with |lambda| on both stable and unstable sides. The temperature strongly affects the spectral shape, with asymmetry at low temperatures and symmetry at high temperatures. A mean-field theory for rho(lambda) based on a heterogeneous elasticity model is proposed and shows good agreement with simulation data.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Chemistry, Physical
Mengkai Feng, Zhonghuai Hou
Summary: We propose a theory to investigate the inertial effect on the glassy dynamics of underdamped active Brownian particle systems. By assuming a nonequilibrium steady-state, an effective Fokker-Planck equation for the probability distribution function (PDF) is obtained. Using this equation, the evolution equation of the intermediate scattering function is derived through the Zwanzig-Mori projection operator method and the mode-coupling theory (MCT). Theoretical analysis reveals that the inertia of the particle affects the memory function and the corresponding glass transition by influencing the structure factor and velocity correlation function. This theory provides theoretical support and guidance for subsequent simulation work.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Review
Chemistry, Multidisciplinary
Indrajit Tah, Anoop Mutneja, Smarajit Karmakar
Summary: Glasses are prevalent in nature and play a significant role in our daily lives. The dynamics of glass-forming systems, ranging from microscopic to macroscopic scales, exhibit slow and heterogeneous behaviors. Recent research has shown that there are growing dynamic and static correlation lengths associated with the observed dynamical heterogeneity and rapid rise in viscosity, highlighting the complexity of glassy dynamics.
Article
Chemistry, Physical
Palak Patel, Mohit Sharma, Sarika Maitra Bhattacharyya
Summary: In polydisperse systems, the correlation between the structural order parameter (SOP) and dynamics depends on the number of species used to describe the system. The SOP at M = 1 shows the highest correlation with dynamics in highly polydisperse systems. The study also suggests that the Vibrality, an order parameter independent of structural information, can be a slightly better predictor of dynamics at high polydispersity due to its strong coupling with particle size.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Xu-Dong Li, Xiao Jin, Zijing Li, Yingdan Liu, Shidong Feng, Li-Min Wang
Summary: The stretched dynamics of structural relaxation in molecular glass formers were investigated using dielectric and thermal relaxations. It was found that the enthalpic relaxation is anticorrelated with the degree of freedom, and a combined parameter was proposed to rationalize the difference in stretching exponents obtained by dielectric and enthalpic relaxations. The interplay between the degree of freedom and dielectric dipole-dipole interaction in molecular dynamics was addressed.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Multidisciplinary Sciences
Hua Tong, Hajime Tanaka
Summary: Understanding the structural ordering upon slow cooling in the absence of crystallization or phase separation is crucial for understanding glass transition. We found that the exotic compositional order has a direct impact on the structural relaxation dynamics, even without any thermodynamic signature. This raises fundamental questions about the role of unconventional structural ordering in glass transition.
NATURE COMMUNICATIONS
(2023)
Article
Physics, Multidisciplinary
Amrita Goswami, Indranil Saha Dalal, Jayant K. Singh
Summary: Using molecular simulations and modified classical nucleation theory, this study investigates the nucleation of various liquids under flow. The results reveal a universal variation of nucleation rate with shear, and a simplified theory successfully explains the nonmonotonic temperature dependence of nucleation behavior.
PHYSICAL REVIEW LETTERS
(2021)
Article
Chemistry, Physical
G. Vazquez, S. Chakravarty, R. Gurrola, R. Arroyave
Summary: High Entropy Alloys (HEAs) are important in metals research and a thorough estimation of the phases in HEA is crucial for alloy design. Machine Learning offers a cost-effective method for predicting new HEAs. A deep neural network model is developed using a dataset generated by high-throughput computational thermodynamic calculations. The model successfully identifies the recurrent phases and can be used for real-time materials discovery/design tasks.
NPJ COMPUTATIONAL MATERIALS
(2023)
Article
Materials Science, Ceramics
John C. Mauro, Charles R. Kurkjian, Prabhat K. Gupta, Walter Kob
Summary: Various impurities in silica glass samples have a significant impact on the glass transition temperature, which can vary by nearly 300 K depending on the type of dopant. A common crossover point is found for all viscosity curves around 2200-2500 K, indicating a change in the transport mechanism from intrinsic defects at high temperatures to dopant-induced defects at low temperatures.
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
(2022)
Article
Physics, Fluids & Plasmas
A. Escobar, F. Donado, R. E. Moctezuma, Eric R. Weeks
Summary: In a quasi-two-dimensional system of magnetic spherical particles on a shallow concave dish under a temporally oscillating magnetic field, the energy losses from collisions and friction with the dish surface are compensated by continuous energy input from the magnetic field. Particle motions resemble that of atoms and molecules in glass or crystal-forming fluid, experiencing an additional force towards the center of the dish due to its curvature. Decreasing the magnetic field leads to decreased effective temperature and slower particle motion, eventually resulting in crystallization and the growth of a hexagonal lattice structure. The study supports nonclassical theories of crystal formation, where initially a dense amorphous aggregate of particles forms and rearranges internally to form the crystalline nucleus before growing into a crystal following classical theory.
Article
Physics, Fluids & Plasmas
Baruch Meerson
Summary: We evaluated the mean escape time of overdamped particles over potential barriers in short-correlated quenched Gaussian disorder potentials in one dimension at low temperature. The form of the tail of the potential barrier probability distribution has a significant impact on the thermally activated escape. We used the optimal fluctuation method to evaluate this tail. We found that for monotone decreasing autocovariances, the obtained tail is consistent with the result obtained by Lopatin and Vinokur (2001). However, for nonmonotonic autocovariances with negative autocorrelations, we observed a higher tail, leading to an exponential increase in the mean escape time. The transition between the two regimes exhibits characteristics of a first-order transition.
Article
Physics, Multidisciplinary
Hajime Tanaka
Summary: This study proposes viscoelastic phase separation as a mechanism to explain the morphology of biological phase separation. By controlling the molecular dynamics between the two phases, different condensate morphologies can be formed. The study reveals the role of molecules in biological phase separation.
COMMUNICATIONS PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Tsuyoshi Kato, Shinji Saito
Summary: In this study, the authors proposed a numerical solution to the inverse Kohn-Sham problem using an integral equation. The accuracy of the calculated exchange-correlation potentials was quantified by evaluating the exchange and correlation energies based on the virial theorem and comparing with the exact ground-state electronic energy. The results showed that the numerical solutions of the integral equation were accurate in reproducing the Kohn-Sham potential and satisfying the virial theorem.
JOURNAL OF THE CHINESE CHEMICAL SOCIETY
(2023)
Article
Physics, Multidisciplinary
Jiaxing Yuan, Kyohei Takae, Hajime Tanaka
Summary: In this study, the role of hydrodynamic interactions (HIs) in the self-assembly of oppositely charged colloidal particles was investigated. It was found that under a constant electric field, HIs lead to the formation of clusters and percolation into a gel network, unlike previous simulations that neglected HIs.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Bhadra Hrishikesh, Kyohei Takae, Ethayaraja Mani, Hajime Tanaka
Summary: We studied the phase separation of a binary mixture of oppositely rotating disks in a two-dimensional viscous fluid. Phase separation formed oppositely flowing bands and a circular rotating droplet, which is due to the nonlinear convective acceleration.
COMMUNICATIONS PHYSICS
(2022)
Article
Chemistry, Physical
Kokoro Shikata, Takuma Kikutsuji, Nobuhiro Yasoshima, Kang Kim, Nobuyuki Matubayasi
Summary: Polymers with functional groups can form hydrogen bonds with water molecules, which creates a strong H-bond network that affects their bulk properties. This study used molecular dynamics simulations to investigate the H-bonding dynamics of water molecules in three poly(meth)acrylates. The results showed that as the water content decreased, the H-bonding dynamics slowed down significantly. The diffusion of water molecules and its relationship with H-bond breakage were also analyzed. The findings suggest that the impact of polymer functional groups on H-bonding dynamics is dependent on the specific interactions between the water molecules and the polymer.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Taichi Inagaki, Miho Hatanaka, Shinji Saito
Summary: In this study, the intermolecular vibration and relaxation dynamics of a water film and a water droplet on a graphene surface were investigated using low-frequency Raman spectra calculated from molecular dynamics simulations. The results showed that the interfacial water systems exhibited weakened libration and enhanced intermolecular hydrogen bond stretching compared to bulk water, indicating softened orientation motion. The study also revealed slower collective polarizability relaxation in the water droplet, which was attributed to positive correlation between induced polarizabilities caused by structural fluctuations. The research demonstrated the revealing capability of low-frequency Raman spectroscopy on the anisotropic and finite effects of intermolecular dynamics in water films and droplets.
JOURNAL OF PHYSICAL CHEMISTRY B
(2023)
Article
Chemistry, Physical
Zhenhao Yu, Rui Shi, Hajime Tanaka
Summary: Water exhibits anomalous thermodynamic and kinetic properties, such as a maximum density at 4 degrees C and a viscosity decrease under pressure. The presence of a second critical point has been attributed to these anomalies. Through extensive molecular dynamics simulations of the TIP4P/2005 water model, we find that a hierarchical two-state model based on cooperative formation of tetrahedral structures via hydrogen bonding can unify the description of the structure, thermodynamic, and kinetic anomalies and criticality of water. This suggests the possible existence of a second critical point in water.
JOURNAL OF PHYSICAL CHEMISTRY B
(2023)
Article
Physics, Multidisciplinary
Hideyo Tsurusawa, Hajime Tanaka
Summary: Experiments reveal a hierarchical structural ordering driven by local potential energy in amorphous gels, making them distinct from amorphous glasses. This ordering is driven by the potential energy, not free energy. These findings will deepen our understanding of gel and glass.
Article
Physics, Multidisciplinary
Yanshuang Chen, Zefang Ye, Kexin Wang, Jiping Huang, Hua Tong, Yuliang Jin, Ke Chen, Hajime Tanaka, Peng Tan
Summary: Glasses can relax internally even when their structure is frozen. In a two-dimensional glass former, non-constrained bonds survive the freezing of structural relaxation, leading to persistent internal relaxation. This study directly visualizes the internal relaxations in a glass through observations of a mechanically driven granular system, revealing the emergence of slow beta relaxation as the structure relaxation freezes.
Article
Chemistry, Physical
Taiki Yanagishima, John Russo, Roel P. A. Dullens, Hajime Tanaka
Summary: Research shows that the preparation protocol of glass determines the crystal growth mode. Traditional glass, prepared by fast quenching, exhibits fast growth with active interface dynamics, while uniform glass, prepared by density homogenization, grows via intermittent avalanche-like dynamics localized at the interface, combining localized mechanical defects and exceptional mechanical stability imposed by the glass phase.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Multidisciplinary Sciences
Hua Tong, Hajime Tanaka
Summary: Understanding the structural ordering upon slow cooling in the absence of crystallization or phase separation is crucial for understanding glass transition. We found that the exotic compositional order has a direct impact on the structural relaxation dynamics, even without any thermodynamic signature. This raises fundamental questions about the role of unconventional structural ordering in glass transition.
NATURE COMMUNICATIONS
(2023)
Article
Multidisciplinary Sciences
Rui Shi, Anthony J. Cooper, Hajime Tanaka
Summary: The behaviour of ions solvated in water is highly ion-specific and can be explained by considering the interplay between ion-water and inter-water interactions as well as the bond-orientational order of the hydration shell. This study provides insight into the ion-specific effects observed in salt solutions and their impact on solution dynamics. The findings have fundamental implications for ionic processes in aqueous solutions, offering a physical principle for electrolyte design and application.
NATURE COMMUNICATIONS
(2023)
Article
Polymer Science
Shota Goto, Kang Kim, Nobuyuki Matubayasi
Summary: This study investigates the static and dynamic behavior of ring polymer melts by molecular dynamics simulations, focusing on the effect of chain stiffness and monomer density. It is found that the dynamics of ring polymers are influenced by excluded volume interactions between centers of mass, as indicated by the increasing non-Gaussianity in the displacement distribution with higher monomer density and stiffness. The relationship between the radius of gyration and monomer density varies with chain stiffness, which can be attributed to the competition between repulsive forces inside and between rings. The dynamic heterogeneity of bond-breakage is coupled with the non-Gaussianity in ring polymer melts, emphasizing the importance of the bond-breaking method in determining the intermolecular dynamics. Overall, this study provides insights into the factors governing the dynamic behaviors of ring polymers.
Article
Physics, Multidisciplinary
Yuan-Chao Hu, Hajime Tanaka
Summary: Nonphononic vibrations have been identified as a fundamental feature that differentiates glasses from crystals. By studying the vibrational properties of three-dimensional model glasses, it has been found that stringlike vibrations are the universal origin of the boson peak in both 2D and 3D glasses with isotropic interactions. Furthermore, these vibrations coincide with the Ioffe-Regel limit of transverse phonons. These findings shed light on the origin of low-temperature glass anomalies and inspire further research.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Chemistry, Physical
Fabio Leoni, Hajime Tanaka, John Russo
Summary: This study numerically investigates the nucleation process during the deposition of a glassformer and compares it with quenched counterpart and bulk system. It is found that all three systems uniformly nucleate crystals within a certain temperature range. The deposited layer shows the formation of ordered domains, with faster relaxation dynamics towards the free surface even in its as-deposited state. Additionally, the nucleus initially grows in an isotropic symmetrical manner but eventually shows sub-3D growth with a preference for growth along the basal plane, regardless of the layer production procedure.
JOURNAL OF MOLECULAR LIQUIDS
(2023)
