We generated approximately Boltzmann-distributed samples using MD by simulating 12,530 non-cyclic molecules from QM9 in vacuum and room temperature using the GAFF force field . We carried out these simulations using the openmmforcefields and OpenMM packages . All initial conditions were generated by energy minimizing the QM9 geometry in the corresponding GAFF force field. We sampled different molecules proportionally to their number of heavy atoms with a median sampling time of 36.5 ns. Moreover, for 100 molecules from the test set (10%), we run longer 100 ns Replica Exchange (RE) simulations. These long RE simulations are used as ground truth in our experiments. We provide further details about the dataset generation and training, validation, and test splits in the Appendices 9.8 and 9.9.