Computer Simulation Methods for Nonadiabatic Dynamics in Condensed Systems

Abstract

As nuclear rearrangements take place during chemical reactions, the reacting molecules can undergo nonradiative electronic excitation or relaxation. These radiationless changes in electronic state or nonadiabatic transitions are particularly important when the electronic states of the reacting system are close in energy, as is often the case for reactions of molecules in excited electronic states. When the energy difference between these close-lying electronic states is comparable to the energy of the nuclear motion, transfer of energy between nuclear and electronic degrees of freedom can have a profound effect on the outcome of these types of reactions. Electronically nonadiabatic effects are thus important in many fundamental molecular processes including: excited-state electronic energy transfer, charge transfer reactions, and quenching of electronic excitation. These types of electronic transitions can also play an important role in chemical reactions of ground-state species at room temperature.