Hagan Group

Reentrant Phase Behavior of Self-Propelled Spheres in 2D with Interparticle Attractions

This movie gives an overview of the phase behavior observed in simulations of self-propelled spheres equipped with Lennard-Jones interactions and confined to a 2D surface.

Each box corresponds to a separate, independent simulation. The axes labels indicate the Peclet number (Pe = ratio of propulsion velocity to diffusion) and the attractive well-depth U of the Lennard-Jones interaction (in units of the thermal energy k_BT). Notice that for moderate attraction strengths (e.g. U=4 k_BT) the phase behavior is reentrant. For low propulsion velocities the system forms or kinetically arrested gel driven by the attractive interactions. As propulsion velocity is increased, the gel first melts into an isotropic fluid, and then undergoes motility-driven phase separation. The simulations are described in G.S. Redner, A. Baskaran, and M.F. Hagan, Phys. Rev. E, 2013. 88: 012305.