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(8月11日15:00)Why does entropy appear to control the relaxation time?

作者: 2017-08-08 17:37 来源:
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  报告题目:Why does entropy appear to control the relaxation time? 

  报告人: Prof. Jeppe C. Dyre 

  Glass and Time, Dept. of Science and Environment, Roskilde University, 

  DK-4000 Roskilde, Denmark 

  时间:2017811(周五) 15:00 

  地点:中科院力学所1号楼344 

  报告摘要: 

  This talk discusses the role of entropy for the relaxation time in, primarily, supercooled glass-forming liquids, but also in less-viscous „ordinary“ liquids. We first briefly summarize early works by Chang & Bestul and by Adam & Gibbs, followed by Rosenfeld's entropy arguments from the 1970's and by Dzugutov's 1996 Nature paper [1]. If time permits the experimental situation will also be summarized. We then jump to developments of the last ten years that have clarified entropy's proposed role via the study of a large class of systems, the so-called R-simple systems comprising most or all van der Waals liquids and metallic liquids, as well as the weakly ionic and/or dipolar liquids. For this class of liquids one may argue that it is not quite correct to state that „entropy controls the relaxation time“ – if anything, it is more accurate to say that „the relaxation time controls the entropy“. In this connection the paper discusses the existence of isomorphs in the phase diagram of R-simple systems and how they „explain“ the role of entropy [2]. 

  1. J. C. Dyre, arXiv:1403.2684 (2014). 

  2. J. C. Dyre, J. Phys. Chem. B 118, 10017 (2014); J. Phys.: Cond. Matt. 28, 323001 (2016). 

  报告人简介: 

  Jeppe C. Dyre earned his Master’s degree in 1984 from the University of Copenhagen and his Ph. D. in 1987 from Roskilde University. He stayed in USA in 1987 and 1988 with Connie Moynihan  and Peter Wolynes, respectively. Since 2000 he has been full professor of physics at Roskilde University where he from 2005 to 2015 directed the center of excellence Glass and Time, which continues thanks to funding by the private VILLUM Foundation. In 2012 Dyre was elected as member of the Royal Danish Academy of Sciences and Letters (founded 1742). Dyre’s research interests originally focused on ac conduction in disordered solids (“random barrier model”) and theories for viscous liquids and the glass transition (“shoving model”). Throughout his career he worked closely with experimentalists. Presently Dyre is engaged in understanding the “hidden” scale invariance of about half of all condensed matter (metals and van der Waals bonded systems, as well as weakly ionic and dipolar systems) and its consequences for the properties of matter. 

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