We investigate transient nonlinear localization, namely the self-excitation of energy bursts in an atomic lattice at finite temperature. As a basic model we consider the diatomic Lennard-Jones chain. Numerical simulations suggest that the effect originates from two different mechanisms. One is the thermal excitation of genuine discrete breathers with frequency in the phonon gap. The second is an effect of nonlinear coupling of fast, lighter particles with slow vibrations of the heavier ones. The quadratic term of the force generate an effective potential that can lead to transient grow of local energy on time scales the can be relatively long for small mass ratios. This heuristics is supported by a multiple-scale approximation based on the natural time-scale separation. For illustration, we consider a simplified single-particle model that allows for some insight of the localization dynamics. © 2021
Mechanisms for transient localization in a diatomic nonlinear chain / Lepri, S.; Piazza, F.. - In: COMMUNICATIONS IN NONLINEAR SCIENCE AND NUMERICAL SIMULATION. - ISSN 1878-7274. - ELETTRONICO. - 102:(2021), pp. 105913-105913. [10.1016/j.cnsns.2021.105913]
Mechanisms for transient localization in a diatomic nonlinear chain
Lepri, S.;Piazza, F.
2021
Abstract
We investigate transient nonlinear localization, namely the self-excitation of energy bursts in an atomic lattice at finite temperature. As a basic model we consider the diatomic Lennard-Jones chain. Numerical simulations suggest that the effect originates from two different mechanisms. One is the thermal excitation of genuine discrete breathers with frequency in the phonon gap. The second is an effect of nonlinear coupling of fast, lighter particles with slow vibrations of the heavier ones. The quadratic term of the force generate an effective potential that can lead to transient grow of local energy on time scales the can be relatively long for small mass ratios. This heuristics is supported by a multiple-scale approximation based on the natural time-scale separation. For illustration, we consider a simplified single-particle model that allows for some insight of the localization dynamics. © 2021I documenti in FLORE sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.