Coherent motions and clusters in a dissipative Morse ring chain

We study a one-dimensional ring chain of length L with N particles interacting via Morse potentials and influenced by dissipative forces (passive and active friction). We show that by negative friction the system can be driven far from the thermodynamic equilibrium states. For over-critical pumping with free energy several types of coherent motions including uniform rotations, optical oscillations and waves emerge in the ring. We also show the existence of a critical particle density n(c) = N/L-c, below that the particles spontaneously organize into clusters which can actively rotate. Additionally, the influence of white noise on the clustering is discussed.