著者

Chiba Ayano Funamori Nobumasa Nakayama Kazuya Ohishi Yasuo Bennington Stephen Rastogi Sanjay Shukla Anuj Tsuji Kazuhiko Takenaka Mikihito

出版者

American Physical Society

雑誌

Physical Review E (ISSN:15393755)

巻号頁・発行日

vol.85, no.2, 2012-02

被引用文献数

20

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溶融高分子の新しい構造変化を発見-加圧によるナノスケールの構造変化-. 京都大学プレスリリース. 2012-02-28.

著者

Charbonneau P. Ikeda A. Meel J. A. van Miyazaki K.

出版者

American Physical Society

雑誌

Physical review E (ISSN:15393755)

巻号頁・発行日

vol.81, no.04, pp.040501, 2010-04

被引用文献数

30 13

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There exists a variety of theories of the glass transition and many more numerical models. But because the models need built-in complexity to prevent crystallization, comparisons with theory can be difficult. We study the dynamics of a deeply supersaturated monodisperse four-dimensional (4D) hard-sphere fluid, which has no such complexity, but whose strong intrinsic geometrical frustration inhibits crystallization, even when deeply supersaturated. As an application, we compare its behavior to the mode-coupling theory (MCT) of glass formation. We find MCT to describe this system better than any other structural glass formers in lower dimensions. The reduction in dynamical heterogeneity in 4D suggested by a milder violation of the Stokes-Einstein relation could explain the agreement. These results are consistent with a mean-field scenario of the glass transition.

著者

Sawada A. Koga T.

出版者

American Physical Society (APS)

雑誌

Physical review e (ISSN:24700045)

巻号頁・発行日

vol.95, no.2, pp.23309, 2017-02-21

被引用文献数

10

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We have developed a method to calculate the weak localization and antilocalization corrections based on the real-space simulation, where we provide 147 885 predetermined return orbitals of quasi-two-dimensional electrons with up to 5000 scattering events that are repeatedly used. Our model subsumes that of Golub [L. E. Golub, Phys. Rev. B 71, 235310 (2005)] when the Rashba spin-orbit interaction (SOI) is assumed. Our computation is very simple, fast, and versatile, where the numerical results, obtained all at once, cover wide ranges of the magnetic field under various one-electron interactions H' exactly. Thus, it has straightforward extensibility to incorporate interactions other than the Rashba SOI, such as the linear and cubic Dresselhaus SOIs, Zeeman effect, and even interactions relevant to the valley and pseudo spin degrees of freedom, which should provide a unique tool to study new classes of materials like emerging 2D materials. Using our computation, we also demonstrate the robustness of a persistent spin helix state against the cubic Dresselhaus SOI.

著者

Kiyono Ken Konno Hidetoshi

出版者

American Physical Society

雑誌

Physical review E (ISSN:15393755)

巻号頁・発行日

vol.87, no.5, pp.052104, 2013-05

被引用文献数

9 3

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As a possible generalization of Beck-Cohen superstatistical processes, we study non-Gaussian processes with temporal heterogeneity of local variance. To characterize the variance heterogeneity, we define log-amplitude cumulants and log-amplitude autocovariance and derive closed-form expressions of the log-amplitude cumulants for χ2, inverse χ2, and log-normal superstatistical distributions. Furthermore, we show that χ2 and inverse χ2 superstatistics with degree 2 are closely related to an extreme value distribution, called the Gumbel distribution. In these cases, the corresponding superstatistical distributions result in the q-Gaussian distribution with q=5/3 and the bilateral exponential distribution, respectively. Thus, our finding provides a hypothesis that the asymptotic appearance of these two special distributions may be explained by a link with the asymptotic limit distributions involving extreme values. In addition, as an application of our approach, we demonstrated that non-Gaussian fluctuations observed in a stock index futures market can be well approximated by the χ2 superstatistical distribution with degree 2.

著者

Suda Yusuke Okuda Koji

出版者

American Physical Society (APS)

雑誌

Physical review E (ISSN:15393755)

巻号頁・発行日

vol.92, no.6, 2015-12-14

被引用文献数

35

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Chimera states in the systems of nonlocally coupled phase oscillators are considered stable in the continuous limit of spatially distributed oscillators. However, it is reported that in the numerical simulations without taking such limit, chimera states are chaotic transient and finally collapse into the completely synchronous solution. In this Rapid Communication, we numerically study chimera states by using the coupling function different from the previous studies and obtain the result that chimera states can be stable even without taking the continuous limit, which we call the persistent chimera state.

著者

Mizuno Hideyuki Yamamoto Ryoichi

出版者

The American Physical Society

雑誌

Physical Review E (ISSN:15393755)

巻号頁・発行日

vol.82, no.3, 2010-09

被引用文献数

17

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We numerically examine dynamical heterogeneity in a highly supercooled three-dimensional liquid via molecular-dynamics simulations. To define the local dynamics, we consider two time intervals: τα and τngp. τα is the α relaxation time, and τngp is the time at which non-Gaussian parameter of the Van Hove self-correlation function is maximized. We determine the lifetimes of the heterogeneous dynamics in these two different time intervals, τhetero(τα) and τhetero(τngp), by calculating the time correlation function of the particle dynamics, i.e., the four-point correlation function. We find that the difference between τhetero(τα) and τhetero(τngp) increases with decreasing temperature. At low temperatures, τhetero(τα) is considerably larger than τα, while τhetero(τngp) remains comparable to τα. Thus, the lifetime of the heterogeneous dynamics depends strongly on the time interval.

著者

Jizba Petr Arimitsu Toshihico

出版者

American Physical Society

雑誌

Physical review E (ISSN:15393755)

巻号頁・発行日

vol.69, no.2, pp.026128, 2004-02

被引用文献数

51 26

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Despite recent claims we argue that Rényi’s entropy is an observable quantity. It is shown that, contrary to popular belief, the reported domain of instability for Rényi entropies has zero measure (Bhattacharyya measure). In addition, we show that the instabilities can be easily emended by introducing a coarse graining into an actual measurement. We also clear up any doubts regarding the observability of Rényi’s entropy in (multi)fractal systems and in systems with absolutely continuous probability density functions.

著者

Arimitsu T. Arimitsu N.

出版者

American Physical Society

雑誌

Physical review E (ISSN:1063651X)

巻号頁・発行日

vol.61, no.3, pp.3237-3240, 2000-03

被引用文献数

86 110

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The analysis of the fully developed turbulence with the help of the binomial multiplicative process is reinvestigated from the standpoint of Tsallis nonextensive statistics in order to provide some insight in understanding the underlying physical meaning of the Tsallis ensemble. The formula is derived which relates Tsallis index q with the intermittency exponent μ that is a manifestation of multifractality of the sizes of eddies. It is shown that the probability density function of the local dissipation of turbulent kinetic energy can be represented by a distribution function of the type in Tsallis statistics with the index q determined by the experimentally observable quantity μ through the derived formula.

著者

Kobayakawa T. S. Hatsugai Y. Kohmoto M.

出版者

American Physical Society

雑誌

Physical review E (ISSN:1063651X)

巻号頁・発行日

vol.51, no.6, pp.5365-5370, 1995-06

被引用文献数

9 9

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Recently, the smoothed correlation between the density of eigenvalues of Hermitian random matrices was found to be universal, that is, independent of the probability distribution from which the random matrices are taken. We study this universal correlation numerically by ensemble averaging, using the Monte Carlo sampling method. Although the density of eigenvalues and the ‘‘bare’’ correlation between the density of eigenvalues are certainly not universal, we find that the smoothed correlation indeed shows a universal behavior. The orthogonal and the symplectic ensembles are also studied numerically. The smoothed correlation is shown to be universal in these cases.

著者

Arimitsu Toshihico Arimitsu Naoko

出版者

American Physical Society

雑誌

Physical review E (ISSN:1063651X)

巻号頁・発行日

vol.50, no.1, pp.121-137, 1994-07

被引用文献数

6 16

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A general formula of the time-resolved optical spectrum for transient resonant light scattering is derived systematically by means of the operator algebra within the formalism of nonequilibrium thermo field dynamics (NETFD). The formula is applied to an analytically solvable model of the localized electron and phonon system, i.e., second-order light scattering due to the optically active three electronic states whose intermediate state is dynamically modulated by the phonon interaction mode. The derivation of the analytical expression for a four-point function, needed to obtain the spectrum, is performed with the help of the algebraic manipulations in NETFD, which showed the advantage of its methodology with respect to nonequilibrium transient phenomena. The three-dimensional profiles of the Raman and luminescence components in the time-resolved spectrum in the model are presented to show how the stochastic character comes out in the fast modulation limit, and how the dynamical behavior of the phonon system causing the modulation of the intermediate electronic state comes out in the slow modulation limit.

著者

Nomura Shintaro Iitaka Toshiaki

出版者

American Physical Society

雑誌

Physical review E (ISSN:15393755)

巻号頁・発行日

vol.76, no.3, pp.037701, 2007-09

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A linear scale method for calculating electronic properties of large and complex systems is introducedwithin a local density approximation. The method is based on the Chebyshev polynomialexpansion and the time-dependent method, which is tested on the calculation of the electronicstructure of a model n-type GaAs quantum dot.

著者

Yoshida Kyo Kaneda Yukio

出版者

American Physical Society

雑誌

Physical review E (ISSN:1063651X)

巻号頁・発行日

vol.63, pp.016308, 2000-12

被引用文献数

17 20

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A model of randomly advected solenoidal field is presented. The model is formally derived by a linearization of the Navier-Stokes equation with respect to the perturbation to a basic state and by assuming the characteristic time scale of the basic state to be very short. The model includes a nonlocal (in space) effect through a pressurelike term that keeps the advected field solenoidal, but still yields exact equations for multipoint moments. The advecting field is assumed to be statistically homogeneous and isotropic with zero mean and structure function with exponent xi. An analysis is made of the scaling of the steady second-order moments of the solenoidal field in two dimensions. The scaling exponent zeta(l) of the isotropic part (l=0) and the anisotropic part for the angular wave number l=2 is obtained analytically or numerically. The scaling of the isotropic part does not depend on whether the pressurelike term is present or not while the scaling of the anisotropic part is affected by the pressurelike term. There are two homogeneous similarity solutions with real positive exponents zeta(2) when xi>xi(c)(2) approximately 1.3. The same kind of analysis is also applied to a simplified two-point closure equation.