Vibrational resonances in 1D Morse and FPU lattices
  In the present paper the resonances of vibrational modes in one-dimensional random Morse lattice are found and analyzed. The resonance energy exchange is observed at some values of elongation. Resonance $2 \omega_1 = \omega_2$ is investigated in details. The interacting modes are inequivalent: the higher-frequency mode is much more stable in the excited state, i.e. its life-time is larger than the life-time of lower-frequency mode under the resonance conditions. Simple model of two nonlinearly coupled harmonic oscillators is also considered. It allows to get analytical description and to investigate the kinetics and the energy exchange degree vs. such parameters as the resonance detuning and specific energy. The very similar behavior is found in the Morse and the two-oscillatory models, and an excellent agreement between analytical and numerical results is obtained. Analogous resonance phenomena are also found in the random Fermi-Pasta-Ulam lattice under contraction. 
T. Yu. Astakhova, N. S. Erikhman, V. N. Likhachev, and G. A.   Vinogradov