A statistical description of systems that are far from equilibrium has been a topic of growing research in the last few years.  In the field of colloidal science, this research has been stimulated by recent developments which allow us to synthesize “active” colloidal particles in the lab.  Active colloids refer to synthetic particles that move by converting energy into motion, for example chemical (e.g. Ref [1]) or magnetic energy (e.g. Ref [2]). The realization of active colloidal particles opens the possibility of creating new materials with various applications. However, the lack of a unified theoretical framework makes the need for theoretical description and predictions via computer simulations a necessity.

In the present project we are investigating the dynamical structures that emerge in systems of active colloidal particles.  To this end, we use Molecular Dynamics and Brownian Dynamics algorithms to study active systems in silico and explore the resulting out-of-equilibrium phase behavior.

Figure 1: Snapshot of a simulation, showing active repulsive squares in crystal-gas phase coexistence caused by kinetic trapping of particles. Particles that belong to the same crystalline domain are colored the same.

[1] Theurkauff, I., et al., Physical Review Letters 108 (26), 268303 (2012)

[2] Bricard, A., et al., Nature 503 (7474), 95 (2013)