Figure shows the first component of the NAC vector for photo-excited ethylene with and without the extrapolation correction scheme for a single (2,2) SA-CASSCF trajectory with identical initial conditions. Without the correction, the NAC clearly undergoes discontinuous jumps due to the sign swaps, whereas the NAC with correction smoothly evolves along the trajectory. Figure and Figure show the corresponding S 2 and S 1 occupations along the trajectory, with substantial deviations observed after 10 fs.