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物理讲坛(2019年第26讲)

发布日期:2019-12-23 作者:物理科学与技术学院 文章来源:未知  责任编辑:

报告题目:The Necessary and Sufficient Condition For Glass Transition
报告人:孙得彦 华东师范大学 教授
报告时间:12月23日 15:30
报告地点:116会议室

摘要:The intrinsic nature of glass states or glass transitions has been a mystery for a long time. Recently, more and more studies tend to show that, a glass has a relatively flat potential energy landscape (PEL). However, this only indicates that, a flat PEL is a necessary condition for forming a glass state or occurring glass transitions. What is sufficient condition for glass formation or glass transition? Here we demonstrate that, a flat PEL is not only a necessary but also a sufficient condition for the formation of a glass. By adjusting the flatness of PEL, we show that: (1) no matter what the structural symmetry is, as long as a system locates in a region of PEL deepen enough, it can undergo a first-order solid-liquid phase transition; and (2) if a system locates in a region of PEL flat enough, it can undergo a glass transition, independent on its structural symmetry. Our molecular dynamics simulations uncover the direct transfer from one potential energy minimum to another below the glass transition temperature, which is the flat feature of PELs. This kind of transition is accomplished by a cooperative motion, which is a direct reflection of assumption for transtion in metabasin and for chain-like motions of the Adam-Gibbs’s entropy theory.

报告人简介:孙得彦,1998年在中国科学院固体物理研究所获得博士学位。2001年至2003年在美国西北大学材料科学与工程系作博士后研究。2004年调入华东师范大学物理系任教授,博士生导师。曾于1998年获中国科学技术大学高等研究院第一届研究生论文竞赛一等奖,中国科学院伟华奖一等奖;2004年获上海市教委曙光学者称号。在国外核心期刊发表论文百余篇。主要科研成果包括:从理论上预言了一种新的滚动扩散机制;提出一种新的等压分子动力学方法;发现了固液界面的结构依赖性;从理论上预言一种新的团簇熔化行为等。研究领域包括计算凝聚态物理新方法的探索,材料设计与模拟,低维凝聚态物理等。主持科研基金包括;国家自然科学基金重点子项目;国家自然科学基金面上项目;上海市教委曙光人才基金;上海市科委浦江人才基金等。

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