The non-adiabatic molecular dynamics simulations use an in-house-modified version of the SHARC nonadiabatic molecular dynamics code, interfaced to the MOLPRO electronic structure package. On-thefly electronic structure calculations are performed at the level of state-averaged complete active space selfconsistent field (SA-CASSCF) approach. Ethylene, fulvene, methyliminium cation, and 1,2-dithiane were calculated with 3SA-CASSCF(2,2), 2SA-CASSCF(6,6), 2SA-CASSCF(6,5), and 3SA-CASSCF(6,4), respectively. All simulations were performed with the 6-31G* basis set. These SA-CASSCF parameters were taken from Refs. 67 and 68. In all cases, only the two lowest-energy, singlet adiabatic states, S 0 and S 1 , were used in the electronic dynamics with the initial electronic state always set to the first singlet excited state, S 1 . Unless otherwise specified, in all ab initio results, the timestep for the nuclear propagation was 0.1 fs using 200 electronic substeps per nuclear step. Further, 1000 trajectories were computed for each molecular model. To be clear, in the spin-PLDM correlation function, each initially focused electronic conditions {λ, λ } was converged with the 1000 trajectories, in total 2 × 2 × 1000 = 4000 trajectories for each of the two-state chemical models.