Evidence for an unusual dynamical-arrest scenario in short-ranged colloidal systems

Extensive molecular dynamics simulation studies of particles interacting via a short-ranged attractive square-well potential are reported. The calculated loci of constant diffusion coefficient D in the temperature-packing fraction plane show a reentrant behavior, i.e., an increase of diffusivity on cooling, confirming an important part of the high volume-fraction dynamical-arrest scenario earlier predicted by theory for particles with short-ranged potentials. The more efficient localization mechanism induced by the short-range bonding provides, on average, additional free volume as compared to the hard-sphere case and results in faster dynamics.