Theoretical Division, Center for Nonlinear Studies,
Mail Stop B258, Los Alamos National Laboratory,
Los Alamos, NM 87545 USA

Non-adiabatic dynamics in electron phonon coupled system

We consider an interacting two-electron system linearly coupled to the vibrational harmonic degree of freedom, focusing on the nonlinear dynamics of the vibrational wavepackets. This problem has significant importance in understanding vibrational dynamics in photo-excited biomolecules. The non-adiabatic coupling between the ground and excited state adiabatic surfaces is analyzed in detail, and found to be significant at the crossing points. This corresponds to the scattering of the ground state vibration wavepackets into the excited state adiabatic surfaces, and eventually to the lost of the coherence between the excited and the ground state wavepackets. This effect should have a clear signature in the nonlinear optical response, which we are currently investigating.