All molecular dynamics simulations in explicit solvation boxes were preceded by 10 ns of NpT equilibration of the bulk solvent, followed by additional 10 ns runs after insertion of the HTI molecule. Apart from the gas phase, photoswitching was investigated in nhexane and dimethyl sulfoxide (DMSO) using cubic, 3D-periodic simulation models of 508 and 991 solvent molecules, respectively. For each isomer, Z and E, parallel systems were prepared and propagated for 50 ns in the NpT ensemble to provide volume relaxation. While 2 ns were found necessary for equilibration, the occurrence profiles of the torsion angle in the different states were derived from the remaining sketches of 48 ns. We then fixed the box volume to the mean volume of the NpT equilibration run and performed an additional NVT run of 50 ns, taking snapshots at every 10 ps. This provided 5,000 structures referring to the (solvated) Z-and Estructures in the S0 state that were used as the starting structures for investigating photoexcitation to S1. The trajectories of the actual switching events were propagated in the NVE ensemble, using an initial 20 ps run in the S1 state and then instantaneously switching back to the S0-FF to produce additional 5 ps NVE runs that describe the S1 → S0 switching, respectively.