Fig. 2.

Illustration of the sigma profile space (Top Left corner) as the collection of all sigma profiles available in the Mullins et al. (30) database, its conversion to an abstract, two-dimensional space (Lower Left corner) for visualization purposes through PCA, and the exploration of the sigma profile digital space through gradient search, aiming at maximizing boiling temperature. The three-dimensional surface (Top Middle) represents the GP-predicted boiling temperature for each sigma profile point, superimposed on the two-dimensional abstract PCA space. Highlighted sigma profiles in all depictions represent successive iterations (i.e., molecules) of gradient search, starting at carbon monoxide (blue) and ending at tetraphenylmethane (yellow).