SISSO models were trained following the same procedure used in Ref. . The same primary features were used (also provided in the PAH101 dataset), with the exception of DF_s and DF_c, because the DFT estimate for the SF driving force is not a physically meaningful descriptor in relation to the fundamental band gap. The same 10 structures as in Ref. were withheld as an unseen test set and the remaining 91 structures were used for model training. Features were constructed with a maximum rung (the number of times primary features are combined) of 3 and a maximum dimension (Dim) of 4. Features were combined using the operator set H = {+, -, ×, ÷, exp, log, () -1 , () 2 , () 3 , √ , 3 √ , | • |}. The maximum complexity, i.e., the maximum number of operators in one combined feature, was set to 10. A total of 5 × 10 2 , 4 × 10 5 , and 6 × 10 10 features were generated by SISSO with a rung of 1, 2, and 3, respectively.