REGULAR AND CHAOTIC DYNAMICS IN SYSTEMS WITH EXCITONIC-VIBRONIC COUPLING

An analysis of a dynamical system presenting a semiclassical descripti on of electronic excitations on molecular dimers, including explicitly their interaction with intramolecular vibrational degrees of freedom, is performed. The transition from regular to chaotic dynamics, which depends on the coupling strength and the total energy, is analysed by presenting Poincare sections in both the excitonic and vibronic variab les. It is shown that, with increasing total energy, chaos develops in the region of the excitonic ground state which is subjected to a bifu rcation For high energies chaos is spread globally over the Bloch sphe re containing, however, regular islands located in the region of the e nergetically higher excitonic antisymmetric state.