Eliminating the need for failure-prone state-tracking algorithms is crucial in order to make SF-TDDFT into a robust, black-box engine for TSH simulations, but elimination of spin contamination has practical consequences for excited-state optimizations and MECP searches. An example of the latter, for an S 0 /S 1 MECP of ethylene, is presented in Fig. in the form of an "optimization trajectory", i.e., a plot of energy (for both S 0 and S 1 ) versus optimization steps. Using conventional SF-TDDFT, singlet and triplet states quickly become mixed so that already by the third optimization step it is difficult to assign spin multiplicities based on the value of Ŝ2 alone. At the third step, the two lowest-energy states have Ŝ2 = 1.14 and Ŝ2 = 0.90 (in units of h2 ), indicating nearly equal mixing of singlet and triplet. Flags on steps 3, 4, 6, 7, 8, . . . in Fig. indicate points at which the state assignment is ambiguous. Energies of the two selected adiabats are strongly oscillatory, suggesting that the algorithm may be switching between states with differing amounts of singlet character, confounding the optimization algorithm. In contrast, the SA-SF-TDDFT optimization proceeds relatively smoothly and converges in far fewer steps. It is worth noting, however, that no analytic gradient has yet been reported for SA-SF-TDDFT, so MECP optimizations at that level of theory are proof-of-concept exercises based on finite-difference gradients. As a second example of SA-SF-TDDFT, we consider the classic strong correlation problem of twisting C 2 H 4 about its C-C axis. The (π) 2 and (π * ) 2 electron configurations become degenerate at a twist angle of 90 • , causing single-reference methods based on spin-restricted orbitals to exhibit an unphysical cusp. Potential energy surfaces for the lowest three singlet states are plotted in Fig. , computed using several different SF methods and compared to a multireference benchmark. Both the simple SF-TDDFT method as well as SA-SF-TDDFT afford reasonably good agreement with the benchmarks for all three of the lowest singlet states, with no unphysical cusps. SA-SF-CIS results are also free of cusps although the absence of dynamical correlation causes the S 1 and S 2 surfaces to deviate significantly from the benchmarks.