EFFECTS OF NEXT-NEAREST-NEIGHBOR HOPPING INTERACTION ON THE STRUCTUREOF ELECTRONIC-ENERGY BANDS OF POLYDIACETYLENES

Starting from the extensional model Huckel Hamiltonian containing the next-neighbor hopping interactions, the energy band structure and thei r variation have been studied for polydiacetylenes (PDA's). With the i ncrease of the next-neighbor hopping interaction parameter rho the res ults show that: (1) the electronic state symmetry is broken, (2) the l ocations and the widths of energy bands have been changed, and (3) the energy gap becomes narrower and the total bandwidth broader. Finally, the effect of the next-neighbor hopping interactions on the band-stru cture is discussed.