title: Pattern formation and localization in the forced-damped Fermi-Pasta-Ulam lattice.
abstract: We study spatial pattern formation and energy localization in the dynamics of an anharmonic chain with quadratic and quartic intersite potential, subject to an optical, sinusoidally oscillating field and a weak damping. The zone-boundary mode is stable and locked to the driving field below a critical forcing that we determine analytically using an approximate model, which describes mode interactions. Above such a forcing, a standing modulated wave forms for driving frequencies below the band edge, while a "multibreather" state develops at higher frequencies. Of the former, we give an explicit approximate analytical expression, which compares well with numerical data. At higher forcing, space-time chaotic patterns are observed.
authors.affiliation: Dipartimento di Energetica "Sergio Stecco," Università di Firenze, Via Santa Marta, 3 - I-50139 Firenze, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Khomeriki
authors.forename: S
authors.initials: S
authors.lastname: Lepri
authors.forename: S
authors.initials: S
authors.lastname: Ruffo