The dimer and monomer HOMO DFT data collected in this study, in conjunction with Equation 2, allowed for the calculation of 𝛽 #' . This quantity is a measure of the relative delocalization of electron density between the HOMO orbitals of the monomers in each of the 4095 dimer pairs. Using Equation 2 and substituting the LUMO energy of monomer A, the LUMO energy of monomer B, the LUMO+1 energy of dimer AB, and the LUMO energy of dimer AB for 𝛼 # , 𝛼 ' , E1 and E2 respectively, 𝛽 #' 5643 was also calculated for each of the 4095 dimer pairs. The 𝛽 values calculated in HMO theory are negative valued. Large negative 𝛽 values imply the monomers interact with high delocalization of electron density across the molecule, while less negative 𝛽 values (𝛽 à 0) indicate that electrons are more localized. A large portion of the 𝛽 #' 2343 and 𝛽 #' 5643 values that were calculated from the thiophene data set were complex numbers. This suggests that the simple secular determinant shown in Equation 1 is poorly described by HMO theory. The diversity of orbital mixing motifs illustrated in Figure , particularly the case of significant charge transfer interactions, likely contribute to the abundance of complex 𝛽 values. Histograms of (𝛽 #' 2343 ) + and (𝛽 #' 5643 ) + are shown in Figure .