Unusual Dynamics of Tetrahedral Liquids Caused by the Competition between Dynamic and Structural 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 the decrease in the diversity of tetrahedra motifs (structural heterogeneity) and the increase of glassy dynamic heterogeneity. This result may contribute to new understandings of the unusual properties of tetrahedral liquids.