Computational Physics of Active Matter

From cytoskeletal macromolecules and micron-sized bacteria to giant fish swarms, active-matter systems occur on all scales throughout nature. These systems are internally driven out of equilibrium and therefore allow for the emergence of a plethora of complex phenomena that are essential for life. In this chapter, we illustrate the unique power of computer simulations to provide a quantitative understanding of active matter. First, basic active-matter model systems are described, including biological and synthetic self-propelled objects, where the driving mechanism is modeled on different levels of abstraction. Second, focusing on bacterial motion, we will discuss the role of hydrodynamic interactions for collective swimming and the role of activity for the rheology of dense bacterial colonies. Third, we will provide examples of active agents that are coupled together by interacting with deformable manifolds such as filaments and membranes. This leads to diverse non-equilibrium shapes, deformations, and motility modes. Finally, some results of simulations of active gels, multicellular growing structures and artificial phoretic swimmers are shown, illustrating the extraordinary diversity of computational active-matter systems.