... rule of increasing number of nodes. A smallband width corresponds to small overlap integrals of the monomer orbitals. J M. André, J. Delhalle,J L. Brédas, Quantum Chemistry Aided Design of Organic ... is certainly non-satisfactory: jmax=∞. In practice, however, we often take jmaxas being of the order of a few cells,most often we take47jmax=1.• For each k from the FBZ we calculate ... structure of polyparaphenylene (π-bands). The COs (in centre) builtas in-phase or out -of- phase combinations of the benzene π molecular orbitals (left-hand side). It is seenthat energy of the COs...