Fig. presents the photodissociation of ethylene through its S 1 /S 0 conical intersection generated by the rotation of the H-C-C-H dihedral angle. The nuclear dynamics of ethylene are analogous to the dynamics of the molecular Tully model #1, as discussed in previous reports. In this model and ab initio system, the wavepacket encounters a single nonadiabatic event, a conical intersection (CI) in this case. This localized crossing represents the simplest nonadiabatic effect in the present work, which is demonstrated by the simplistic population dynamics in Fig. . Even so, all of the semiclassical quantum dynamics approaches fail to capture the entirety of the population dynamics compared to the AIMS benchmark (blue).