Konstantin Sergeev

The dynamics of a triangular lattice consisting of active particles is studied. Particles with nonlinear friction interact via nonlinear forces of Morse potential. Nonlinear friction slows down fast particles and accelerates slow ones. Each particle interacts mainly with the nearest neighbors due to the choice of the cut-off radius.
Stationary modes (attractors) and metastable states of the lattice are studied by methods of numerical simulation.
It is shown that the main attractor of the system under consideration is the so-called translational mode — the state with equal and unidirectional velocities of all particles. For some parameter values translational modes with defects in the form of vacancies and interstitial particles are possible.
Metastable localized states are presented by the plane soliton-like waves (M-solitons) with inherent velocity and density maxima. The lifetime of such states depends on the lattice parameters and the wavefront width. All metastable states transform into the translational mode after a transient process.

The dynamics of a dense ensemble of interacting active Brownian particles is studied. Nonlinear negative friction is described in the sense of Rayleigh; particles are interconnected via Morse potential forces. Such a chain can be considered as an ensemble of interconnected Rayleigh oscillators.
The stationary modes (attractors) of chains with periodic boundary conditions looks like cnoidal waves. They are characterized by a uniform distribution of the density maxima of particles in the chain. However, when the chain starts with random initial conditions, a state of nonuniformly distribution of density maxima arises first. This state is metastable and the transition to a stable mode corresponds to a long transition process.
Characteristics of metastable states, regularities and probability of their occurrence and their lifetimes are studied by methods of computer simulation.