In many molecules, the potential energy surface includes coupling across multiple torsion angles due to intramolecular non-bonded interactions, with protein backbone torsion angles (ϕ, ψ) being a well-known example. Ethylene glycol is an example of a molecule with strong intramolecular interactions between the hydroxyl functional groups. Figure compares the results of a 1D torsion drive started from one initial conformation (indicated with +) and multiple initial conformations (indicated with *) together with a 2-D torsional PES. These calculations were performed within the QCArchive infrastructure that provides TorsionDrive calculations as a service, as described in Section 4.2. Energies and gradients were calculated using the B3LYP-D3(BJ) functional and DZVP basis optimized for DFT as implemented in the Psi4 software package, and optimizations were carried out using the geomeTRIC software. The results show that a 1D torsion scan started from a conformation where the hydroxyl groups are facing in opposite directions (4b upper) will fail to find the lowest energy con- 3.4 Generalized dihedral scanning and restricted grid TorsionDrive has several additional features for flexibility in setting scanning coordinates for different molecular systems. First, the scanned coordinate(s) are not required to be strict definitions of proper torsion angles as four atoms in three sequential covalent bonds; any dihedral angle defined by four atom indices can be scanned, such as generalized torsion angles defined by four non-consecutive atoms or improper torsion angles describing pyramidalization. Second, the scan range can be restricted to focus computations on regions of interest, in case certain ranges of the dihedral angle are not physically reasonable.