At the beginning of the simulated dynamics, t = 10 fs in Fig. (left panel), the TDPES along q is basically a potential well with minimum between q = -2 and q = 0 where the nuclear density is localized; along ϕ and in the region q ∈ [-2, 0] the TDPES is slightly more flat than along q, so as to allow the density to spread towards the CIs. This shape resembles the adiabatic S 1 PES, since at this early time, nuclear dynamics fully takes place in the excited state.