Turning to SAPT0 to quantify interaction energy components (i.e., electrostatic versus dispersion) further highlights differences between the categories of close contacts. The nonspecific contacts behave most similarly to the weakest CH-p stacking or hydrogen bonding interactions, suggesting that they may include some favorable dispersive and electrostatic contacts without forming stacking interactions or hydrogen bonds. CH-p stacking interactions have a favorable one-to-one relationship between the electrostatic and dispersion energies (Figure ). Thus, although CH-p stacking interactions are predominantly thought to be dispersive, the electrostatic contribution is significant. In contrast, hydrogen bonding interactions are stabilized more by the electrostatic contribution, which outweighs the dispersion component by a factor of two on average (Figure ). While both interaction types have energetic contributions from dispersion and electrostatic energies, we previously noted that CH-p stacking interactions are more favorable overall than the hydrogen bonding interactions we examined. Although both interactions have a similar electrostatic contribution, the CH-p stacking interaction has a considerably larger favorable dispersion contribution. All other close contacts that form two or fewer C-H interactions (i.e., less than our criteria for CH-p stacking) or a non-specific contact have an intermediate contribution from dispersion and electrostatic energies. Next, we compared the interaction strengths of CH-p stacking interactions formed by tryptophan, tyrosine, and phenylalanine. While the 410 relevant interactions in our dataset have hybrid DFT interaction energies that range from -10.1 to -2.1 kcal/mol, the strongest are those formed with tryptophan, the most highly enriched amino acid in protein-carbohydrate binding pockets 23 (Figure ). These CH-p stacking interactions are more energetically favorable on average by 3 kcal/mol than those formed with tyrosine and phenylalanine (Figure ). Tryptophan has a larger and more electron-rich aromatic ring system enabling more favorable CH-p contacts and stronger dispersion and electrostatic energy contributions (Supporting Information Figure ). (right) CH-p stacking interactions formed with tyrosine with e=10 (green), deprotonated tyrosine in its phenoxide form with e=10 (purple), tyrosine with e=80 (light green), and phenoxide with e=80 (light purple). Each box is bounded by the upper and lower quartiles of the dataset and split by the median; it contains the interquartile range. The whiskers extend up to 1.5 times the interquartile range on either side of the box. All points that lie outside that range are defined as outliers and shown as filled diamonds on the left plot and filled circles on the right plot. The IEs were evaluated using the aug-cc-pVDZ basis set and are reported in kcal/mol.