The Thermodynamic and Dynamic Behavior of Supercooled Water During Fragile-to-Strong Crossover

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Live Poster Session: https://wesleyan.zoom.us/j/99443973421?pwd=bGFaMXprMGJ2b0RrSyszVFMxbG05UT09

Hongjia Zhang
Hongjia Zhang

Hongjia (Jane) Zhang is a BA/MA student in Physics. Hongjia comes from Beijing, China. During her undergraduate years, Hongjia double-majored in philosophy and physics. At Wesleyan, Hongjia explored different fields of natural sciences and developed her newfound interest in ballet. Hongjia also co-chaired the POC (People of Color) Pre-Law Society. In her spare time, Hongjia listens to a lot of true crime podcasts, enjoys taking walks in nature and having conversations with friends.

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Abstract: Water is ubiquitous and people are familiarized with the fact that water manifests itself in its solid, liquid, and gas forms in nature. However, the dynamics and thermodynamics behind the phase diagram of water are not fully understood. In its supercooled region (below 0 °C/273 K), water undergoes a novel “fragile-to-strong crossover,” effectively changing its behavior from one type of liquid to another. My computational physics project with Professor Francis Starr studies supercooled water during this “fragile-to-strong crossover”. From our thermodynamic data of the isobaric heat capacity (Cp) and structure factor (S(q)), I first identify the thermodynamics signature of the crossover. Water’s dynamic heterogeneity (χ4) from the high- to the low-temperatures (290 K – 200 K) first increases, reaches a peak at 205 K and eventually decreases. The decrease in dynamic heterogeneity below 205 K is consistent with our hypothesis that the crossover is a consequence of the water structure reaching an energetically stable random tetrahedral network as temperature decreases. Our new findings from the TIP4P/2005 model are compared and contrasted with our group’s previous work with the ST2 model. We have found a match in supercooled water’s dynamic and thermodynamic behavior during similar regimes.

Introduction Video:

Jane-Zhangs-Summer-Research-Poster

Live Poster Session:
Thursday, July 29th 2:45-3:45 pm EDT