An extended SU(2) model for coupled Morse oscillators Original Research Article

The SU(2) vibron model has been shown to correspond to an approximation where only the dominant Δv=±1 interaction between Morse oscillators is taken into account [A. Frank, R. Lemus, M. Carvajal, C. Jung, E. Ziemniak, Chem. Phys. Lett. 308 (1999) 91]. We extend the algebraic model in order to incorporate higher-order couplings for the Morse oscillators, thus, providing a means to establish an exact quantum-mechanical connection with traditional phase-space descriptions of molecular vibrations. Results for the energy spectrum for two coupled Morse oscillators are compared with both the traditional and extended SU(2) models, as well as with the Child–Lawton model. The wave functions corresponding to the different models are also examined. A classical analysis is carried out in order to further explore the interrelations between these models.