Breakdown of the Stokes-Einstein relation in Lennard-Jones glassforming mixtures with different interaction potential

The breakdown of the Stokes-Einstein relation was investigated for three glass-forming models composed of mixtures of Lennard-Jones A - B particles, which have been constructed by modifying the shape of the interaction potential between A particles. By performing molecular dynamics simulations, we show that these mixtures intrinsically possess different organizations. The breakdown of the Stokes-Einstein relation particularly occurs at different temperatures for each type of particles and it is directly related to the dynamical decoupling between A and B particles and the formation or not of paths where fast particles show jumplike motions. The effective size of each particles and the fraction of slow and fast particles were also determined. Similarity with silicate glasses including mixed alkali effect is discussed.