where "𝛼 # " is the HOMO energy of monomer A, "𝛼 ' " is the HOMO energy of monomer B, and "𝛽 #' " is the resonance integral representing the extent of interaction between the HOMO orbitals of monomers A and B when combined into dimer AB. The solution of this determinant yields two energy values: E1 is equal to the HOMO energy of dimer AB, and E2 is equal to the HOMO -1 energy of dimer AB. Solving Equation 1 for 𝛽 #' yields Equation 2.