Spectra in the chaotic region: A classical analysis for the sodium trimer

Abstract
Classical mechanics is used to compute the low resolution spectrum of Na3 in the chaotic regime. The regularity in the spectrum is shown to be due to a family of C2v symmetry tori involving a high amplitude breathing mode and a high amplitude bending mode. These tori are the two mode survivors of the three mode tori whose quantization gives the four assignable lower energy vibrational levels.