Squeezed states in the trimer problem

In the present work we study unconventional (''squeezed'') exciton-phonon states in the trimer model. These quasifree states, which do not undergo self-trapping, are characterized by a nearly vanishing lattice distortion and a stiffening in the phonon part as well as a large amount of kinetic energy in the excitonic subsystem. In contrast, the ''conventional'' exciton-phonon states are characterized by a strong lattice distortion and physically amount to a self-trapping of the exciton. In the trimer model a third type of exciton-phonon states have been found, which are a kind of ''dimerized'' states, where self-trapping has taken place only partially. The different types of states are analyzed and discussed. (C) 1996 American Institute of Physics.