University of Cambridge > Talks.cam > TCM Informal Seminar Series > Understanding liquids and glass transition on the basis of elastic interactions

Understanding liquids and glass transition on the basis of elastic interactions

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Existing textbook expressions for the energy and heat capacity of gases and solids are widely taught in physics courses. However, no such expression exists for a liquid. Based on the old idea of Frenkel, I formulate this problem in the language of phonons, and calculate liquid energy and heat capacity for both the classical and quantum cases.

I subsequently address the old and very controversial problem of glass transition, and propose the solution that is based on elastic interactions in a liquid. Central to this discussion is the range of propagation of high-frequency elastic waves in a liquid, which I call “liquid elasticity length d”. d measures the range over which local relaxation events in a liquid elastically interact with each other via the elastic waves they induce. d is small at high temperature, and increases on lowering the temperature. This sets the cooperativity of molecular relaxation in a liquid, and gives the famous Vogel-Fulcher-Tammann law. In this picture, I also discuss other central properties of glass transition: the absence of divergence at a finite temperature, the origins of two dynamic crossovers and the origin of liquid “fragility” (Angell plot).

This talk is part of the TCM Informal Seminar Series series.

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