THEORETICAL-STUDIES ON QUASI-DIABATIC ELECTRONIC EFFECTS IN LITHIUM HEAVILY-DOPED POLYACETYLENE

A quasi-diabatic crystal orbital (CO) theory earlier developed has bee n applied to lithium heavily-doped trans-polyacetylene (t-PA) to study quasi-diabatic electronic effects in a metallic state. It has been sh own that the quasi-diabatic electronic structure largely changes from the adiabatic electronic structure. This change arises from the strong interaction of the crystal momentum coupling between carbon pi and li thium canonical COs. The coupling also leads to occurrence of a large spin-density-wave (biradical character) in the quasi diabatic electron ic state. The occurrence has been analyzed to be due to a large electr on-electron repulsive interaction. The quasi-diabatic electronic struc ture has been discussed with a focus on the electron-electron repulsio n.