TRANSLATIONALLY-INVARIANT POLARONS IN CONJUGATED CONDUCTING POLYMERS

A simple effective Hamiltonian for the electron-phonon coupling in the conjugated polymers is derived from the Su-Schrieffer-Heeger model wi th quantized lattice motions. Phonons correspond to lattice quantum fl uctuations around the dimerized positions. Both acoustic and optical m odes are considered. The energy-momentum relation for the polaron is c alculated variationally, with the aid of Lee-Low-Pines transformation. The discrete translational invariance of an ideal conjugated polymer is. explicitly enforced. Analytical expression for the polaron effecti ve mass m is obtained. m* turns out to be, in general, much larger th an the conduction-band effective mass.