We had previously discussed the possible influence of using CASPT2 to parametrize the LVC potentials in the Supporting Information of Ref. 1. There, we argued that using CASPT2 in place of CASSCF energies would lead to three differences. First, the 3 T 1 ′ --→ 3 A 2 internal conversion would be partially quenched through shifting of 3 A 2 energies. This hypothesis is realized in the CASSCF/CASPT2 dynamics, that now show only 50% of the population moving via the 3 T 1 ′ --→ 3 A 2 pathway compared to the 70% of the CASSCF dynamics. Second, the long-lived singlet population would increase through partial quenching of the Sing --→ 3 T 2 back-intersystem crossing. This second hypothesis is also realized in the CASSCF/CASPT2 dynamics The CASSCF/CASPT2 dynamics thereby not only show a larger total retention of singlet population at extended simulation times, i.e., 9% in the CASSCF/CASPT2 dynamics vs. 1% in the CASSCF dynamics. The CASSCF/CASPT2 dynamics also show a larger relative retention, as the singlet population falls from the maximum of 43% to 9%, i.e,. to ca. a fifth of its maximum value, while it falls from 10% to 1%, i.e., a tenth of its maximum value in the CASSCF dynamics. Third, we argued that due to the stabilization of the 3 T 1 ′ states, they may receive more population during the dynamics which in turn could lead to larger population transfer to the singlet states. While the first part of this hypothesis has not been proven fulfilled, i.e., there is not more population channel through the 3 T 1 ′ states in the CASSCF/CASPT2 dynamics compared to the CASSCF dynamics, we find indeed larger population in the singlet states in the CASSCF/CASPT2 dynamics. This might be partially ascribed to less population being transferred to the 3 DL states in the CASSCF/CASPT2 dynamics which can be due to the stabilization of the 3 T 1 ′ states.