Motility-induced phase separation of deformable particles

Motility induced phase separation (MIPS), the phenomenon in which purely repulsive motile particles phase separate into high and low density phases, is a landmark of active matter physics. As such, this transition has been widely studied, with extensions covering different types of interactions, particle shapes, confinements and biologically inspired features such as division, which breaks number conservation. Nevertheless, the literature generally considers rigid particles of fixed shape. In this work, we employ a multi-phase field model to study MIPS in assemblies of deformable particles in two dimensions and quantify how deformability alters the phase diagram. We find that highly deformable particles are less propense to phase separate, as dense clusters tend to fluidize with increasing deformability. We also examine the structural and dynamical properties of the clusters. We expect that generalizing the study of MIPS to systems of deformable particles will increase our understanding of its relevance to biological settings, such as cellular tissues.