The electronic band structure of polydiacetylenes with second- and third-neighbor hopping interaction

We have studied the energy band structure of polydiacetylenes (PDAs) using the extensional Huckel Hamiltonian that includes the nonnearest-neighbor ho pping interactions. The results show that with increase in the nonnearest-n eighbor hopping interaction parameters rho (1) and rho (2), (i) the energy band symmetry is broken and the energy gap 2 Delta has changed, (ii) the lo cations and the widths of energy bands have changed and their shifts depend mainly on rho (1) (next-neighbor hopping interactions), and (iii) the ener gy gap 2 Delta depends mainly on rho (2) (third-neighbor hopping interactio ns), the effects of the nonnearest-neighbor hopping interaction on the band structure are discussed.