Delocalized nonlinear vibrational modes and discrete breathers in ß-FPUT simple cubic lattice.

ABSTRACT

The problem of finding various discrete breathers (DBs) in the ß-Fermi-Pasta-Ulam-Tsingou simple cubic lattice is addressed. DBs are obtained by imposing localizing functions on delocalized nonlinear vibrational modes (DNVMs) having frequencies above the phonon spectrum of the lattice. Among 27 DNVMs with the wave vector at the boundary of the first Brillouin zone there are three satisfying this condition. Seven robust DBs of different symmetries are found using this approach.