In comparison to the TDDFT methodology, the CASSCF-based surface hopping simulations display notable discrepancies in their dynamic evolution. A comparison of the population dynamics for each isomer in the gas phase, as derived from the two quantum than the perturbative treatment in TDDFT. It is noteworthy that the CASSCF approach yielded results that are in accordance with the previous analysis of 2-TP in the gas-phase. However, a faster ISC and triplet state dynamics is observed in the current CASSCF implementation than the previous one. This could be a consequence of different basis sets and state-averaging (more number of singlet and triplet states in this study) used in the two studies. On the other hand, more unexpected features are obtained for the other two isomers. As shown in Figure , the CASSCF simulation for 3-TP maintains the population of S 4 in a manner analogous to the TDDFT approach, but discrepancies are observed for the other states. Specifically, CASSCF yields significantly smaller populations for S 2 , S 1 , and the triplet states compared to TDDFT. Additionally, the multiconfigurational approach presents population decay to the ground state, as evidenced by the rising S 0 populations.