Sub-Arrhenius diffusion in a binary colloidal system

The dynamics of binary colloidal mixture subjected to an external potential barrier is investigated using molecular dynamics simulations. The depletion interactions between the potential barrier and larger components of the mixture alters the dynamics of the system significantly. The larger particles undergo sub-Arrhenius diffusion while smaller particles obey normal Arrhenius diffusion. These results show that quantum phenomena such as tunneling is not required to have sub-Arrhenius diffusion, in contrast to the general agreement in the literature. The depletion interactions between the external potential barrier and larger component increases with decreasing temperature which makes the effective activation energy for barrier crossing temperature dependent leading to sub-Arrhenius diffusion.