ased on the known crystal data , we used the EHMACC(EHMO/CO) methodto calculate the twotlimensional energy band of both undoped and heavily iodine-doped polyacetylene (PA). The results show that (1 ) I-doping obviousl...ased on the known crystal data , we used the EHMACC(EHMO/CO) methodto calculate the twotlimensional energy band of both undoped and heavily iodine-doped polyacetylene (PA). The results show that (1 ) I-doping obviously reducesthe niagnitudes of Eg , Egi; (2) in the conducting process along the direction per-pendicular to PA chain , the P-type AO of iodine plays a very important role, i- e. ,the conducting bridge to transport the charge between the two neighbor PA chains.I-doping reniarkably increases σ_T value while the conducting process will reduce theratio magnitude of σ/σ. Therefore, heavily I-doping makes PA change fromsimeconductor to conductor which obviously has 2-D conductive ability.展开更多
We use extended Huckel methods of molecular orbitds and crystal orbitals (EHMO/CO) to calculate the two-dimensional band structures of highly oriented trans-polyacetylene (PA) undoped and doped with SO3. According to ...We use extended Huckel methods of molecular orbitds and crystal orbitals (EHMO/CO) to calculate the two-dimensional band structures of highly oriented trans-polyacetylene (PA) undoped and doped with SO3. According to the energy band theory of solids, we explain the changes of band gap (Eg) and bandwidth (BW) from undoped PA to SO3-doped PA, and discuss the electrical anisotropy of oriented trans-polyacetylene doped with SO3. The calculated results show that the conductivity anisotropy ratio (σ///σ⊥) is determined by Eg and BW in the directions both parallel (σ//) and perpendicular (σ⊥) to the PA chains, respectively. The conductivity anisotropy ratio σ///σ⊥ decreases when PA is doped with SO3, because the dopant plays a conjugated bridge role between the interchains of PA, and makes the dopant itself and PA chains show a strong interchain coupling. The theoretical results for undoped and doped PA are in good agreement with experimental ones.展开更多
文摘ased on the known crystal data , we used the EHMACC(EHMO/CO) methodto calculate the twotlimensional energy band of both undoped and heavily iodine-doped polyacetylene (PA). The results show that (1 ) I-doping obviously reducesthe niagnitudes of Eg , Egi; (2) in the conducting process along the direction per-pendicular to PA chain , the P-type AO of iodine plays a very important role, i- e. ,the conducting bridge to transport the charge between the two neighbor PA chains.I-doping reniarkably increases σ_T value while the conducting process will reduce theratio magnitude of σ/σ. Therefore, heavily I-doping makes PA change fromsimeconductor to conductor which obviously has 2-D conductive ability.
文摘We use extended Huckel methods of molecular orbitds and crystal orbitals (EHMO/CO) to calculate the two-dimensional band structures of highly oriented trans-polyacetylene (PA) undoped and doped with SO3. According to the energy band theory of solids, we explain the changes of band gap (Eg) and bandwidth (BW) from undoped PA to SO3-doped PA, and discuss the electrical anisotropy of oriented trans-polyacetylene doped with SO3. The calculated results show that the conductivity anisotropy ratio (σ///σ⊥) is determined by Eg and BW in the directions both parallel (σ//) and perpendicular (σ⊥) to the PA chains, respectively. The conductivity anisotropy ratio σ///σ⊥ decreases when PA is doped with SO3, because the dopant plays a conjugated bridge role between the interchains of PA, and makes the dopant itself and PA chains show a strong interchain coupling. The theoretical results for undoped and doped PA are in good agreement with experimental ones.