While all the quantities discussed above can be directly obtained from the system wavefunction, constructing theses quantities from an ensemble of surface hopping trajectories is not a trivial task. For a trajectory ensemble, we can generally express the distribution function ( , (20), the population of state i and the indicator of coherence betweIn states i and j can be easily calculated using Eqs. ( ) and (19). However, each surface hopping trajectory can generate two types of time-dependent information: the active states and the electronic wavefunctions. We can only obtain the population distribution ( ,