Note that even though the trajectory-averaged population-transfer coming from the CT term is zero, the quantum momentum can induce population transfer associated with an individual trajectory, a mechanism that is lacking in traditional methods . The modified definition of the quantum momentum (Q m ) resulting from Eq. ( ) has been successfully applied in CTMQC calculations of photo-induced molecular dynamics . This condition of zero net population transfer in regions of zero NAC may be viewed as an exact condition to be imposed within the algorithm, as we will shortly do for the conservation of total energy .