Nonadiabatic dynamics of excited excess electrons in simple fluids

We present a surface hopping trajectory method for studying nonadiabatic excess electronic relaxation in condensed systems. This approach is used to explore the nonadiabatic relaxation after photoexciting an equilibrated excess electron in dense fluid helium. We survey the different types of nonadiabatic phenomena which are important in excess electronic relaxation. Very rapid diabatic processes are common when the nuclear dynamics provides only weak couplings between the adiabatic states. This is generally the case when the states are localized in different regions of space. We find that the nuclear dynamics provides a mechanism for strong coupling between s‐ and p‐like states localized in the same solvent cavity. These strong nonadiabatic interactions can persist over a wide range of nuclear configurations and for many hundreds of femtoseconds.