We investigate nonadiabatic dynamics of molecular sodium in two alternative approximate ways. Firstly, the semiclassical mapping formalism is used to study the decisive step in resonant two photon ionization of Nan, where the Rabi oscillations of the occupation probability of the resonantly excited intermediate state are reproduced with a high degree of accuracy. Secondly, nonadiabatic quantum molecular dynamics is combined with the surface hopping approach of Tully in order to take into account quantum effects on the nuclear dynamics in collisionally excited sodium molecular ions. Their importance is demonstrated by comparing the results with experimental fragment correlations of kinematically complete experiments.