The torsion profile of the core HTI molecule features two (local) energetic minima in each, the S0 and S1 states, respectively (figure ). Using unrestrained geometry optimization from DFT calculations, we prepared reference models of these key structures. The underlying S0/S1 type minimum energy structures of HTI are used for computing the atomic partial charges of the MM models. Starting from the DFT-relaxed S0-E and S1-syn structures, rigid scans of the -C=Ctorsion were performed in parallel runs. While such rigid scans are particularly useful for parameterization of the torsion potentials without interference from lateral movements, we suggest the fully relaxed minimum energy configurations S0-Z/E and S1-syn/anti for benchmarking our MM models.