- 著者
- Kim Kang Miyazaki Kunimasa Saito Shinji
- 出版者
- IOP Publishing
- 雑誌
- Journal of physics. Condensed matter (ISSN:09538984)
- 巻号頁・発行日
- vol.23, no.23, pp.234123, 2011-05
- 被引用文献数
- 40 26
Using molecular dynamics simulations, we study the slow dynamics of supercooled liquidsconfined in a random matrix of immobile obstacles. We study the dynamical crossover fromglass-like to Lorentz-gas-like behavior in terms of the density correlation function, the meansquare displacement, the nonlinear dynamic susceptibility, the non-Gaussian parameter, and thefragility. We find the cooperative and spatially heterogeneous dynamics to be suppressed as theobstacle density increases, leading to a more Arrhenius-like behavior in the temperaturedependence of the relaxation time. Our findings are qualitatively consistent with the results ofrecent experimental and numerical studies for various classes of spatially heterogeneoussystems. We also investigate the dependence of the dynamics of mobile particles on theprotocol used to generate the random matrix. A re-entrant transition from the arrested phase tothe liquid phase as the mobile particle density increases is observed for a class of protocols.This re-entrance is explained in terms of the distribution of the volume of the voids that areavailable to the mobile particles.
- 著者
- Ozawa Misaki Kuroiwa Takeshi Ikeda Atsushi Miyazaki Kunimasa
- 出版者
- American Physical Society
- 雑誌
- Physical review letters (ISSN:00319007)
- 巻号頁・発行日
- vol.109, no.20, pp.205701, 2012-11
- 被引用文献数
- 56 6
Recent studies show that volume fractions φJ at the jamming transition of frictionless hard spheres and disks are not uniquely determined but exist over a continuous range. Motivated by this observation, we numerically investigate the dependence of φJ on the initial configurations of the parent fluid equilibrated at a volume fraction φeq, before compressing to generate a jammed packing. We find that φJ remains constant when φeq is small but sharply increases as φeq exceeds the dynamic transition point which the mode-coupling theory predicts. We carefully analyze configurational properties of both jammed packings and parent fluids and find that, while all jammed packings remain isostatic, the increase of φJ is accompanied with subtle but distinct changes of local orders, a static length scale, and an exponent of the finite-size scaling. These results are consistent with the scenario of the random first-order transition theory of the glass transition.
- 著者
- Ikeda Atsushi Miyazaki Kunimasa
- 出版者
- American Institute of Physics
- 雑誌
- The journal of chemical physics (ISSN:00219606)
- 巻号頁・発行日
- vol.135, no.2, pp.024901, 2011
- 被引用文献数
- 15
We numerically study thermodynamic and structural properties of the one-component Gaussian core model at very high densities. The solid-fluid phase boundary is carefully determined. We find that the density dependence of both the freezing and melting temperatures obey the asymptotic relation, log Tf, log Tm∝ − ρ2/3, where ρ is the number density, which is consistent with Stillinger's conjecture. Thermodynamic quantities such as the energy and pressure and the structural functions such as the static structure factor are also investigated in the fluid phase for a wide range of temperature above the phase boundary. We compare the numerical results with the prediction of the liquid theory with the random phase approximation (RPA). At high temperatures, the results are in almost perfect agreement with RPA for a wide range of density, as it has already been shown in the previous studies. In the low temperature regime close to the phase boundary line, although RPA fails to describe the structure factors and the radial distribution functions at the length scales of the interparticle distance, it successfully predicts their behaviors at longer length scales. RPA also predicts thermodynamic quantities such as the energy, pressure, and the temperature at which the thermal expansion coefficient becomes negative, almost perfectly. Striking ability of RPA to predict thermodynamic quantities even at high densities and low temperatures is understood in terms of the decoupling of the length scales which dictate thermodynamic quantities from the interparticle distance which dominates the peak structures of the static structure factor due to the softness of the Gaussian core potential.
- 著者
- Markland Thomas E. Morrone Joseph A. Miyazaki Kunimasa Berne B. J. Reichman David R. Rabani Eran
- 出版者
- American Institute of Physics
- 雑誌
- The journal of chemical physics (ISSN:00219606)
- 巻号頁・発行日
- vol.136, no.7, pp.074511, 2012
- 被引用文献数
- 34 7
A comprehensive microscopic dynamical theory is presented for the description of quantum fluids as they transform into glasses. The theory is based on a quantum extension of mode-coupling theory. Novel effects are predicted, such as reentrant behavior of dynamical relaxation times. These predictions are supported by path integral ring polymer molecular dynamics simulations. The simulations provide detailed insight into the factors that govern slow dynamics in glassy quantum fluids. Connection to other recent work on both quantum glasses as well as quantum optimization problems is presented.
- 著者
- Ikeda Atsushi Miyazaki Kunimasa
- 出版者
- American Institute of Physics
- 雑誌
- The journal of chemical physics (ISSN:00219606)
- 巻号頁・発行日
- vol.135, no.5, pp.054901, 2011
- 被引用文献数
- 27 8
We numerically study crystal nucleation and glassy slow dynamics of the one-component Gaussian core model (GCM) at high densities. The nucleation rate at a fixed supercooling is found to decrease as the density increases. At very high densities, the nucleation is not observed at all in the time window accessed by long molecular dynamics (MD) simulation. Concomitantly, the system exhibits typical slow dynamics of the supercooled fluids near the glass transition point. We compare the simulation results of the supercooled GCM with the predictions of mode-coupling theory (MCT) and find that the agreement between them is better than any other model glassformers studied numerically in the past. Furthermore, we find that a violation of the Stokes-Einstein relation is weaker and the non-Gaussian parameter is smaller than canonical glassformers. Analysis of the probability distribution of the particle displacement clearly reveals that the hopping effect is strongly suppressed in the high density GCM. We conclude from these observations that the GCM is more amenable to the mean-field picture of the glass transition than other models. This is attributed to the long-ranged nature of the interaction potential of the GCM in the high density regime. Finally, the intermediate scattering function at small wavevectors is found to decay much faster than its self part, indicating that dynamics of the large-scale density fluctuations decouples with the shorter-ranged caging motion.
- 著者
- Ikeda Atsushi Miyazaki Kunimasa
- 出版者
- American Institute of Physics
- 雑誌
- The journal of chemical physics (ISSN:00219606)
- 巻号頁・発行日
- vol.135, no.2, pp.024901, 2011-07
- 被引用文献数
- 15 16
We numerically study thermodynamic and structural properties of the one-component Gaussian core model at very high densities. The solid-fluid phase boundary is carefully determined. We find that the density dependence of both the freezing and melting temperatures obey the asymptotic relation, log Tf, log Tm∝ − ρ2/3, where ρ is the number density, which is consistent with Stillinger's conjecture. Thermodynamic quantities such as the energy and pressure and the structural functions such as the static structure factor are also investigated in the fluid phase for a wide range of temperature above the phase boundary. We compare the numerical results with the prediction of the liquid theory with the random phase approximation (RPA). At high temperatures, the results are in almost perfect agreement with RPA for a wide range of density, as it has already been shown in the previous studies. In the low temperature regime close to the phase boundary line, although RPA fails to describe the structure factors and the radial distribution functions at the length scales of the interparticle distance, it successfully predicts their behaviors at longer length scales. RPA also predicts thermodynamic quantities such as the energy, pressure, and the temperature at which the thermal expansion coefficient becomes negative, almost perfectly. Striking ability of RPA to predict thermodynamic quantities even at high densities and low temperatures is understood in terms of the decoupling of the length scales which dictate thermodynamic quantities from the interparticle distance which dominates the peak structures of the static structure factor due to the softness of the Gaussian core potential.