Energy level statistics for the regular energy spectrum of nonlinear triatomics: Nongeneric aspects and quantum chaos

摘要

We examine the regular energy spectrum of a nonlinear triatomic using model systems for which there is no coupling between the vibrational modes. We calculate the second and third moments of the successive spacing distribution and show that these may differ from those found for a generic regular energy spectrum in an energy range above the potential energy barrier for going through the linear geometry. Consequently, for nonlinear triatomics, caution must be exercised in using energy level statistics as evidence for the existence and degree of quantum chaos.