Theoretical Study of Glass Transition and Slow Dynamics

玻璃化转变和慢动力学的理论研究

基本信息

批准号：
06640509
负责人：
ODAGAKI Takashi
金额：
$ 1.47万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06640509/
关键词：
glass transition slow relaxation and fast process ideal three mode model trapping diffusion model non-gaussianity molecular dynamics simulation Vogel-Fulcher law alpha-and beta-relaxation 遅い緩和速い過程ノンガウシアニティー二成分ソフトスフェア-系 Vogel-Ful

项目摘要

The main theme of the present research project is to understand the dynamical properties of vitrification process in a unified manner and to elucidate the physics of the glass forming process. We studied the trapping diffusion model (TDM) more throughly and gave the theoretical foundation of the model. We also performed a molecular dynamics simulation to find out the changes in dynamical properties of supercooled liquids.We extended the TDM to include the trapped motion as well as the non-trapped jump motion and obtained the dynamical structure factor. We showed that the main relaxation time obeys the Vogel-Fulcher law and obtained the non-Gaussianity which agees qualitatively with experiments.We also devised a new technique (log-Cole-Cole analysis) with which we can find easily the nature of the relaxation.The extensive MD simulation was carried out for a binary soft shpere system covering the liquid state, supercooled liquid state and glassy state. We found the Vogel-Fulcher law for the main relaxation time, Boson-peak and the fast process.We proposed an ideal three model mode consisting of an oscillation and two kinds of stochastic motions and showed that this model can reproduce the dynamical charasteristics of supercooled liquids.The foundation of the TDM was discussed extensively and it was shown that similar dynamics would be commonly observed in systems with activation processes with randam activation energies. We also showed that the divergence of various moments signifies the dynamical transitions and that the difference of temerature multiplied by the excess entropy from its value the glass transition point can serve as the scaling parameter for the transition.

本研究项目的主题是以统一的方式了解玻璃化过程的动力学特性并阐明玻璃形成过程的物理原理。我们对捕获扩散模型（TDM）进行了更深入的研究，并给出了该模型的理论基础。我们还进行了分子动力学模拟，以找出过冷液体动力学性质的变化。我们将TDM扩展到包括俘获运动和非俘获跳跃运动，并获得了动力学结构因子。我们通过实验证明了主弛豫时间服从Vogel-Fulcher定律，并通过实验得到了定性的非高斯性。我们还设计了一种新技术（log-Cole-Cole分析），通过它我们可以很容易地找到弛豫的本质对涵盖液态、过冷液态和玻璃态的二元软球体系进行了广泛的MD模拟。我们发现了主弛豫时间、玻色子峰值和快速过程的Vogel-Fulcher定律。我们提出了由振荡和两种随机运动组成的理想三模型模式，并表明该模型可以再现过冷的动力学特性TDM 的基础被广泛讨论，结果表明，在具有随机激活能的激活过程的系统中通常会观察到类似的动力学。我们还表明，各种矩的分歧表示动态转变，并且温度差乘以玻璃化转变点值的过量熵可以作为转变的缩放参数。