Decoupling of Self‐Diffusion and Structural Relaxation during a Fragile‐to‐Strong Crossover in a Kinetically Constrained Lattice Gas

Decoupling crossover in glass formers : In normal liquids, the self‐diffusion constant, D s , and mean relaxation time, τ α , are inversely proportional. However, in glass formers, D s and τ α are decoupled, and if fragile–strong crossovers exist, D s τ α versus temperature T can be non‐monotonic. The authors illustrate such a decoupling theoretically using an asymmetry parameter b (see figure). A similar behavior is seen in experiment.