Narrow Results

The title theory is developed by combining the Herman–Kluk semiclassical theory for adiabatic propagation on single potential energy surface and the Zhu–Nakamura theory for nonadiabatic transition. A fairly simple expression for the propagator based on classical trajectories is derived using the Møller operator formulation of scattering theory. The theory takes into account almost all quantum effects that occur during nonadiabatic transition, especially at low energies and is expected to be applicable to general chemical dynamics of high dimensions. Application to a two-dimensional model system shows that the theory works well for the propagation duration of several molecular vibrational periods and wide wave packet energy range.

We study Landau-Zener transitions of a two-level system that is coupled to a quantum heat bath at zero temperature. In particular, we reveal that for a whole class of models, the probability for a nonadiabatic transition is bath-independent.