Cluster Crystals: Equilibrium and Non-equilibrium


We study the appearance and properties of cluster crystals (solids in which the unit cell is
occupied by a cluster of particles) with soft-core repulsive interactions in two different systems:
i) an equilibrium system of Brownian particles in the overdamped limit, and
ii) a system of self-propelled active particles. Despite the particles repel each
other they spontaneously aggregate. We study this phenomenon at two levels of description:
performing numerical simulations of the discrete particle dynamics, and by analysis
of the corresponding Dean-Kawasaki equation for the macroscopic particle density.
In the case of non-equilibrium active particles we show how self-propulsion deforms
the clusters by depleting particle density inside, and for large speeds it melts the crystal.
Based on the papers:
Delfau et al, Physical Review E 94, 042120 (1-13) (2016)
Delfau, Lopez, Hernandez-Garcia, New Journal of Physics, in press (2017)