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, the small B particles remain mobile with a relatively weak decrease in their self-diffusion coefficient D with increasing density. Surprisingly, around ρ, the self-diffusion coefficient of species A, D, 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.