  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.
