It was hypothesized that large dipole moments lead to charge transfer interactions, which cause the abundance of unexpected negative HOMO shifts illustrated in Figure . To test this hypothesis, the dataset was partitioned into three subsets: small HOMO shifts (-0.2 to 0.2 eV), positive HOMO shifts (> 0.2 eV), and negative HOMO shifts (< -0.2 eV). Within each subset, the dimer HOMO shift was plotted versus calculated dimer dipole moment using joint kernel density estimate (KDE) plots. The joint KDE plots for the positive HOMO shift and negative HOMO shift subsets are shown in Figure . While there is little correlation between the dimer HOMO shift and the dimer dipole moment, there are clear differences between the average dipole moments in each subset. The negative HOMO shift compounds have an average dipole moment of 5.6 ± 2.0 D (725 compounds). The positive HOMO shift compounds have an average dipole moment of 3.3 ± 1.9 D (1402 compounds). The compounds with small HOMO shifts (not shown in Figure ) have an average dipole moment of 4.1 ± 2.0 D (1968 compounds). Only the extreme dimer HOMO shift values are shown in Figure to more clearly establish the relationship with the dimer dipole moments.