In fact, it appears that of the 1226 monomers in our data set, only a small subset has been captured by the GA to promote a small HOMO-LUMO gap. In Figure the top 10 most common monomers are highlighted, along with their molecular structures at the bottom. At a first glance some of those monomers show a common electron-accepting motifs, such as monomers 115 and 187 with two highly electron withdrawing nitro groups, or monomer 1212 which is another common acceptor monomer used in various π-conjugated polymers .