Finite-size effects in the diffusion dynamics of a glass-forming binary mixture with large size ratio

Extensive molecular dynamics computer simulations of an equimolar, glass-forming AB mixture with a large size ratio are presented. While the large A particles show a glass transition around the critical density of mode-coupling theory ρ_c, the small B particles remain mobile with a relatively weak decrease in their self-diffusion coefficient D_B with increasing density. Surprisingly, around ρ_c, the self-diffusion coefficient of species A, D_A, also starts to show a rather weak dependence on density. We show that this is due to finite-size effects that can be understood from the analysis of the collective interdiffusion dynamics.