The distribution of these 𝛽 integrals can be partly explained by examining differences in the HOMO or LUMO orbital energies of monomer units prior to dimer formation. HD = The monomer with the higher energy HOMO, "HOMO donor" HA = The monomer with the lower energy HOMO, "HOMO acceptor" LD = The monomer with the higher energy LUMO, "LUMO donor" LA = The monomer with the lower energy LUMO, "LUMO acceptor" Eg = LUMO -HOMO, "HOMO/LUMO Gap"