PROPAGATORS FOR COHERENT MOTION OF EXCITONS IN A DIMERIZED CHAIN WITHONE IMPURITY

The quantum coherent motion of excitons (electrons) in a dimerized cha in with one impurity is studied analytically. The exact solutions for the amplitude propagators are obtained explicitly, from which the effe cts of the impurity and the electron-phonon interaction (which models the dimerized chain) are manifested. The evolution of excitons is foun d to be more and more localized with the increase of the impurity ener gy or the enhancement of the electron-phonon interaction. The symmetry property for the amplitude propagators in the real space is also give n.