vdW and the number of vdW interacting hydrogen atoms n H-H vdW with respect to the hydrogen vdW radius assuming a Lennard-Jones potential for a cluster of 30 water molecules. Welldepth potential ϵ of 0.0007 kcal/mol (hydrogen bonded to oxygen) . The effective vdW radii R eff vdW were computed from Equation 1 by using PBE0/aug-cc-pVTZ atomic and molecular densities. The gray region indicates the most common range of radii employed for hydrogen in prior literature. FIG. . Whisker plot of Hirshfeld volume ratios of H, C, N, O, S, and Cl atoms for the optimized structures within the QM7-X dataset of organic molecules with up to 7 heavy (nonhydrogen) atoms .