Slow dynamics of supercooled liquids confined in random pinning fields: Type A-B relaxations and reentrant transition

We study the slow dynamics of supercooled liquids confined in a random matrix of immobile obstacles via molecular dynamics simulations. The dynamical crossover from glass-like (Type B) to Lorentz-gas-like (Type A) behavior is examined in terms of the intermediate scattering function and the mean square displacement. We also investigate the dependence of the dynamics of mobile particles on the protocol to generate the random matrix. A reentrant transition from the arrested phase to the liquid phase as the mobile particle density increases is observed for a class of protocols. This reentrance is explained in terms of the distribution of the volume of the voids that are available to the mobile particles.