Floquet Hamiltonian for incorporating electronic excitation by a laser pulse into simulations of non-adiabatic dynamics

We present a simple way to incorporate a molecule-field interaction into non-adiabatic molecular dynamics. This makes possible integrated simulation of the photoexcitaion and the ensuing photodynamics, providing accurate initial conditions that are specific for the particular wave-length and duration of the laser pulse. The proposed approach is applied to simulate the dynamics of pyrrole photodissociation. The approach is particularly convenient for the use with ab initio Multiple Cloning approach, but the idea can be implemented in other quantum dynamics methods.