  Accurate simulation of the non-adiabatic dynamics of molecules in excited
electronic states is key to understanding molecular photo-physical processes.
Here we present a novel method, based on a semiclassical approximation, that is
as efficient as the commonly used mean field Ehrenfest or ad hoc Surface
Hopping methods and properly accounts for interference and decoherence effects.
This novel method is an extension of Hellers Thawed Gaussian wavepacket
dynamics that includes coupling between potential energy surfaces. The accuracy
of the method can be systematically improved.
