Theory of Transition Dynamics of Localized Electrons Induced by Lattice Relaxation in Excited States

Dynamics of the nonradiative transition in excited states of localized electrons is studied and clari ed. The nonradiative transition is induced by an o -diagonal interaction between the two states around the potential crossing region. We propose a model for the lattice relaxation by extending the quantum damping theory to a two level system and analyze the transition dynamics numerically. The nonradiative transition goes on two steps; rst during the lattice relaxation process as the phonon wave packet passes the crossing point, then from the relaxed excited state through thermal excitation or quantum tunneling. The di erence of transition dynamics for the amount of lattice relaxation is also discussed.