Thursday, July 14 2022
14:00 - 15:30

IMSc Webinar

The Structure, thermodynamics, and dynamics of supercooled liquid

Arijit Mondal

IISER Tirupati

The idea of glass transition always fascinates the researchers of Statistical Mechanics. When the liquid enters the supercooled region, the dynamics becomes slower and the particles get trapped for an increasingly longer time inside the cages made by their neighbours. Upon further cooling the system becomes metastable and unable to access the entire phase space i.e., the ergodicity breaking of the system occurs. Consequently, the relaxation time or the viscosity of the system increases to a very high value leading to the glass transition of the system. One of the signatures of the ideal glass transition is vanishing configurational entropy. In this lecture, I will present how by adopting classical density functional theory we studied the configurational entropy of a hard-sphere system. The packing fraction at which the configurational entropy vanishes is the Kauzmann packing fraction of the system. This Kauzmann packing fraction depends upon the amorphous structure of the system. Later I will present the same for the general soft-core system like the inverse-n power potential system, where n is the softness parameter. The thermodynamic quantity configurational entropy is related to the dynamic quantity relaxation time through the Adam-Gibbs relation. In our work, the dynamics of the system is quantified by the term fragility. This fragility changes with the change of the softness parameter. Later I will present the link between the dynamic and the elastic properties of the soft-colloids system studied by Weitz et. al.(Nature 462, page 83). Water is known to show many unique thermodynamic and dynamic anomalies in its supercooled state. From the NPT molecular dynamics simulation of TIP4P/2005 water, I will present how these anomalies are hidden in the path of the potential energy landscape. At last, I will present the distribution of diffusion constant and the violation of the Stoke-Einstein relation for supercooled water.

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