Existence of nonlinear resonances in polyethylene

In this paper, we demonstrate that the internal dynamics and vibrational spectra of polyethylene are influenced by Fermi and other nonlinear resonances. In previous work, the first semiclassical theory and quantum numbers (in parabolic coordinates) appropriate for this type of resonance were developed. We find from detailed molecular dynamics simulations that the same types of quantum numbers are applicable for polyethylene stretch-bend mode interactions. In addition, a one-to-one resonance is found to exist from one local CH stretch to another CH stretch along the polymer chain.