Unusual Dynamics of Tetrahedral Liquids Caused by the Competition between Dynamic and Chemical Heterogeneity*

Tetrahedral liquids are intriguing: they don’t pack the entire space, and they form networks of a variety of structures. As a result, tetrahedral liquids often exhibit fascinating phase behaviors like water. In this talk, I will discuss our recent neutron spin echo measurements of the collective dynamics as well as molecular dynamics (MD) simulations, using a neural network forcefield (NNFF), of another prototypical AX2-type tetrahedral network liquid, ZnCl2. We observed an unusual non-monotonic temperature-dependence of the stretching exponent β as the liquid is supercooled. Further simulations revealed that this unusual dynamic behavior is due to the competition between dynamic and chemical heterogeneity. This discovery may provide new insight into the unusual thermodynamic properties of tetrahedral liquids.