The influence of iodine impurity states on dielectric properties of polyethylene

The impurity states of iodine in polyethylene have been studied through the use of density functional theory. A comparison of the impurity states is presented based on their energies, atomic orbital compositions, and the spatial features of their wavefunctions. The comparison shows that the occupied impurity states influence conduction more than the unoccupied impurity state by increasing hole mobility and decreasing the thermal activation energy. A “mixed impurity state” at the VB edge, is extended significantly across chains compared to other impurity states and thus facilitates interchain charge transfer.