The extent to which long-time dynamics of a single tracer particle can be enhanced were tested using a combination of simulations and liquid-state theory in this hot paper. It was found that adding a soft repulsion to interactions with neighbouring particles of a hard-sphere-like tracer particle could significantly enhance the long-time diffusivity.
Enhancing tracer diffusivity by tuning interparticle interactions and coordination shell structure
James Carmer , Gaurav Goel , Mark J. Pond , Jeffrey R. Errington and Thomas M. Truskett
Soft Matter, 2012, Advance Article