for delta correction when compared to a larger basis (aTZ) used in the gold standard reference. And, the RMSE in relative energies for the 7 molecule subset (7 x 24 grid points) of our reference theory with respect to the gold standard was 0.0761 0.0904 0.0609 kcal/mol (the subscript and superscript are the 95% confidence intervals). So, the difference with respect to the gold standard was one tenths of a kcal/mol for our choice of reference theory level, which was accurate enough and quite affordable for our study.