In the TI-ADGA calculation, an average over the ten lowest energy VSCF densities was used in the PES construction. This is a high number of eigenstates to include but since the VSCF states are pairwise degenerate a high number is required in order to ensure that the PES is described in a broad domain. The TI-ADGA calculation required 25 SPs to converge. The dynamics are propagated at the TDH level of theory but by using the MCTDH module in MidasCpp. This is done in order to add the time-dependent pulse. For all simulations, the initial state is the localized VSCF state obtained from the pre-calculated TI-ADGA PES and the simulation time is 2.0•10 5 a.u. (4.838 ps). The amplitude of the pulse in the simulations was A = 1.0 • 10 -5 a.u., the peak position of the pulse was at t p = 3.5 • 10 4 a.u. (846.61 fs), and the phase was ϕ = 0. The angular frequency of the pulse have been chosen to match the excitation energy from the lowest-energy state to the first excited state within the same well obtained from the split basis VSCF calculation, ω = 4.4619 • 10 -3 a.u.