Abstract: Based 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, Eg_⊥; (2) in the conducting process along the direction per-pendicular to PAchain, the P-type AOof iodine plays a very important role, i- e.,the conducting bridge to transport the charge between the two neighbor PAchains.I-doping reniarkably increases σ_T value while the conducting process will reduce theratio magnitude of σ/σ_⊥.Therefore, heavily I-doping makes PAchange fromsimeconductor to conductor which obviously has 2-D conductive ability.

Key words: Conductive polymer, 2-D energy band, Electric anisotropy