The amorphous state is ubiquitous in nature. Many things we see everyday fall into the category of amorphous materials. Window glasses, dense colloidal suspensions, gels, granular materials and foams are just some examples of such systems. These systems challenge a key idea in condensed matter science, namely that the structure assumed by the constituent molecules and atoms underlies the nature of the material. Instead, their overall structure does not show significant changes from the disordered liquid state, but the dynamics gets arrested and the macroscopic system is rigid as it is in crystalline solids.
A recently developed technique consists in biasing the statistics of the trajectory space towards lower mobility of the system, exhibiting a non-equilibrium phase transition between the liquid state and a dynamically arrested state (a glass). Interestingly, it has been found that this transition can be driven also by biasing towards a higher concentration of certain locally preferred structures, suggesting a coupling between local structure and dynamics in glass formers. We employ molecular dynamics simulations and transition path sampling techniques to clarify this interplay and we hope this will improve our knowledge on the mechanisms by which the amorphous state emerges in nature.
Non-Equilibrium Phase Transition in an Atomistic Glassformer: The Connection to ThermodynamicsF. Turci, C.P. Royall, and T. Speck, Phys. Rev. X 7, 031028 (2017)[abstract] [arXiv]