Structural glasses: Flying to the bottom

Singh, Ediger and de Pablo have introduced an algorithm which is a modified molecular dynamics simulation, progressively introducing small groups of particles into the system while locally minimizing the potential energy and slowly reducing the temperature of the added particles. The authors also investigated the mechanism behind the formation of these model low-energy glasses at the single particle level, unambiguously proving that a liquid layer does indeed exist on the surface of the deposited glass, and showed that particles in this layer are characterized by a mobility that is several orders of magnitude larger than that in the bulk. The presence of a free surface brings in a significant simplification to the complexity of the configuration space and a reduction of the intra-basin energy barriers.