ON ENERGY LOCALIZATION IN THE β-FPUT SQUARE LATTICE DURING COLLISIONS OF MOVING DISCRETE BREATHERS

10.25712/ASTU.1811-1416.2026.01.011

Abstract

Interest in nonlinear lattice vibrations is driven, on the one hand, by the existence of spatially periodic discrete systems in nature and technology, and on the other hand, by the fact that in many applications they can be subjected to high-amplitude impacts, which reveal the nonlinear nature of interparticle couplings. An important effect of nonlinearity in discrete periodic structures is the possibility of the existence of spatially localized oscillations of large amplitude, which are called "discrete breathers" (DBs) (or intrinsic localized modes). Oscillations localized at defects can also be realized in the case of linear interactions, but DBs exist in defect-free lattices, but only due to their nonlinearity. This paper presents a computer simulation of the collision of moving DBs emitted by two pairs of oscillating atoms located in the close-packed rows in a square lattice with a Fermi-Pasta-Ulam-Tsingou (FPU) potential. Two pairs of forced oscillating atoms can be located in the same close-packed row or shifted by several rows. In the first case, head-on collisions of discrete breathers are observed; in other cases, discrete breathers interact while moving in parallel close-packed rows. The main scenarios for colliding moving discrete breathers in such a lattice are described, and the maximum lattice energy at the moment of discrete breather collision is calculated. The calculations described above demonstrated that interacting discrete breathers increase the maximum energy of atoms in the system in the collision zone. The increased atomic energy observed during discrete breather collisions can facilitate overcoming potential barriers associated with structural rearrangements