Considering impurity molecules functioning as switches, the charge transpor
t on a single conducting polymer chain is investigated. The dynamics of str
uctural bipolaron-type defects in conjugated polymers using a modified tigh
t-binding hamiltonian is extended to include the effects of an external ele
ctric field and the parameters of the switching molecules are studied. The
electric field is used to accelerate charged bipolarons in polymers and it
is introduced in terms of a time-dependent vector potential, We use the Par
iser-Parr-Pople model combined with the Su-Schrieffer-Heeger model of elect
ron-lattice coupling and a Brazovskii-Kirova-type simmetry-breaking interac
tion. The process of charge transfer through the sites, and that it works l
ike a switch, is analyzed by the numerical resolution of the equations of m
otion within the unrestricted Hartree-Fock approximation. The switching cha
racter of the parameters of the molecules on the charge transport through t
he chain is determined. The energies involved are also discussed. (C) 2001
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