Ultrafast nonadiabatic photodissociation dynamics of F₂ in solid Ar

We explore the ultrafast spin-flip dynamics in a diatomic molecule imbedded in a rare gas matrix using the combination of a quantum mechanical and a semiclassical surface hopping method. Specifically, we investigate (1) the extent to which the phenomenon of electronically-localized eigenstates in strongly-coupled manifolds survives in the presence of rapid decay and a multitude of electronically coupled states; (2) the ability of the surface hopping method to predict the short time dynamics; and (3) the time range over which frozen lattice models are valid. Our results point to the active role played by a large number of coupled electronic states in the F₂/Ar dynamics while substantiating our confidence in the validity of the popular surface hopping approach for the system considered.