Fig. 5. (left) Delineation of selected F-SAPT functional groups. 14 functional groups are shown that are differentiated by ovals that each contain one functional group. Oxygen-containing functional groups are shown in red ovals, the aromatic ring functional group is shown in a blue oval, and all other carbon-containing functional groups are shown with gray ovals. Atoms are colored as follows: carbon in gray, oxygen in red, and nitrogen in blue. (right) F-SAPT visualizations of interaction energy contributions (in kcal mol⁻¹) for representative structures from each of the three categories of tryptophan close contacts with functional groups colored by their interaction energy following the inset colorbar and defined corresponding to the groupings on the left.