Ultrafast excited-state dynamics are at the heart of photofunctional molecules, determining their applicability and efficiency. Timeresolved (pump-probe) experiments utilizing ultrashort (∼ps-fs) pulses are powerful tools to resolve excited-state mechanisms, however, analysis of the obtained data can be problematic, often leading to contradictory interpretations. Theory in particular time-dependent approachescan deliver valuable excited-state data that might be difficult to access by experimental techniques, due to, e.g., limited time resolution and/or overlapping signals. The interplay of experiments and theory thus has a crucial importance in deciphering all details of the ultrafast dynamics. Ideally, quantum dynamics (QD) would be the method of choice for simulating excited-stated dynamics, as it can deliver the exact solution by solving the timedependent Schrödinger equation. However, for transition metal complexes, QD simulations can only be performed in drastically reduced dimension. Trajectory surface hopping (TSH), on the other hand, is operative in full dimension, as nuclear motion is treated classically, but quantum effects are inherently not taken into account (some quantum phenomena can though be introduced approximately such as electronic transitions and decoherence). Recently, we found for Fe complexes that full-dimensionality is by far more important than the rigorous treatment of quantum effects. In our recent works, we simulated the excited-state dynamics of the [Fe(bmip) 2 ] 2+ and [Fe(terpy) 2 ] 2+ complexes using full-dimensional TSH (bmip = 2,6-bis(3-methyl-imidazole-1ylidine)-pyridine, terpy = 2,2':6',2"-terpyridine). These two Fe(II) complexes are important prototypes for ultrafast dynamics between MLCT and metal-centered (MC) states, triggered by MLCT excitation. The Fe-carbene [Fe(bmip) 2 ] 2+ complex is the first-discovered Fe-based photosensitizer 31 with a 3 MLCT lifetime of 9 ps, which is about 100 times larger than the one of Fe(II) polypyridines such as [Fe(terpy) 2 ] 2+ (∼100 fs), leading though to population of the quintet HS MC state ( 5 MC) on a sub-ps timescale (see Figure ). Moreover, for [Fe(bmip) 2 ] 2+ , it turned out that the sce- In the case of [Fe(bmip) 2 ] 2+ , the 5 MC state is neglected, as it does not contribute to the dynamics. The potential energy curves were taken from refs. 26,28. nario is more complicated with a fraction of the 3 MLCT population converted into 3 MC already on sub-ps timescales. All these mechanistic insights were obtained through time-resolved experiments. Importantly, our full-dimensional TSH simulations led to results in good agreement with the experiments and to improved mechanistic interpretations. However, from a methodological point of view, several aspects of the simulations governing the dynamics should be analyzed in higher detail. One of the most important factors impacting the simulated dynamics is the choice of electronic structure method to calculate the potential energy surfaces (PESs), on which the dynamics simulations are carried out. In this work, we exploit the existence of time-resolved experimental data to benchmark electronic structure (density functional) methods for the simulation of excited-stated dynamics of the [Fe(bmip) 2 ] 2+ and [Fe(terpy) 2 ] 2+ complexes.