Recent benchmark studies address the issue of how accurate a quantum mechanical method is with respect to a highly accurate gold standard such as coupled cluster with singles, doubles and perturbative triples in the complete basis set limit (CCSD(T)/CBS). Some studies are from the viewpoint of quantum chemistry method developers, where one would be concerned by a difference of even 0.1 kcal/mol in mean accuracy of absolute energies, with respect to the reference level of theory. However, from the perspective of practitioners engaged in force field development and general biochemical simulations, where relative energies such as conformer energetics and torsional profiles are of primary concern (as emphasized in Sellers et al. ), it is crucial that the quantum mechanical (QM) methods used to generate reference data for force field parametrization can reproduce torsion energy profiles with deviations of approximately 0.5 to 1.0 kcal/mol or smaller. This level of accuracy, as demonstrated in high-level QM calculations, is vital for ensuring the accuracy of trained force fields, and boosts the reliability of property predictions like protein-ligand binding affinities. By achieving accuracy within this specified range for the QM reference data employed in force field parametrization, and assuming the trained force field mimics the QM training data quite well, we can effectively capture the essential conformational behavior and energetic trends exhibited by the molecules under investigation. Our focus here is precisely in this area, conformational energetics, and not on modeling long-range electrostatic interactions, which may involve different considerations. Our primary focus is on accurately modeling small molecule organic compounds within pharmaceutically relevant regions of chemical space using force fields. As a result, we do not concern ourselves with evaluating the performance of quantum mechanical (QM) methods for compounds involving transition elements, lanthanides, noble gases, and other elements not directly implicated in the fundamental molecular interactions governing the binding and recognition of small molecule drugs. At the Open Force Field (OpenFF) Initiative, our attention lies on achieving performance benchmarks for organic molecules within the chemical space that is pertinent to small molecule drugs and that our force fields are currently capable of modeling. This chemical space encompasses C, H, O, N, P, S, F, Cl, Br, and I, as well as the monoatomic ions Li + , Na + , K + , Rb + , F -, Cl -, Br -, and I -.