In contrast, carbon atoms C1, C4, and C6 are involved in some but not all CH-p stacking interactions (Supporting Information Figure ). For this reason, we used the distances dC1-Ctr, dC4-Ctr, and dC6-Ctr to define which portion of the ring participates in the CH-p stacking interaction. This analysis indicated only dC6-Ctr is universally essential in our feature set (see Sec. 3c). Since the identity of the aromatic ring system influences the strength of the CH-p stacking interaction, we considered features that are sums of multiple distances to capture the number and proximity of CH groups interacting with the aromatic ring system and differentiate interactions formed by tryptophan from those formed by tyrosine and phenylalanine. Finally, we selected two composite features to delineate the CH group proximity, dC1-Ctr+dC2-Ctr and dC4-Ctr+dC6-Ctr. These features capture an energetic landscape for CH-p stacking interactions, effectively differentiating interactions by their energetic favorability (Figure ). Importantly, these features contain no direct information regarding the face or orientation of the aromatic ring system. The relative facial positioning and rotation of the aromatic ring(s) has no intrinsic influence on the energetics of the interaction. Conversely, CH group proximity informs the interaction strength (Figure ). That is, the most favorable interactions have the smallest dC1-Ctr + dC2-Ctr and dC4-Ctr + dC6-Ctr values. However, the conformation of galactose, the size of the aromatic ring systems, and the exchange energy prevent the minimization of both features to very small values, giving rise to an energetic tradeoff (Figure ). Exploring this tradeoff, we find that it is possible to form CH-p stacking interactions with maximal interaction strength by minimizing either or both features, and thus, bringing any subset of 3 or more galactose C-H groups into close proximity of the aromatic ring. This demonstrates that CH-p stacking interactions do not have one energetic minimum, but rather, multiple relative orientations give rise to highly favorable CH-p interactions. aromatic amino acids, (center) only tryptophan, or (right) only tyrosine and phenylalanine. Each data point is plotted according to dC1-Ctr + dC2-Ctr versus dC4-Ctr + dC6-Ctr and colored by the B3LYP-D3 DFT interaction energy computed using the aug-cc-pVDZ basis set reported in kcal/mol, according to the color scale shown at the far right. Five data points (A-E) are highlighted on the plots and the corresponding CH-p stacking interactions are shown. Atoms are colored as follows: carbon atoms in gray, oxygen atoms in red, nitrogen atoms in blue, and hydrogen atoms in white.