Quantum dynamics of interacting excitonic-vibronic dimer

摘要

A carrier on a symmetric dimer with a weak hopping integral, interacting (via a site-local coupling) strongly with on-site oscillators is considered. It is shown that the dynamics of the low excited nonstationary states is, owing to strong carrier-oscillator correlations, incompatible with that of the nonlinear Liouville equation theory. The oscillators are, owing to carrier-oscillator correlations, fully relaxed to the instantaneous rather than to the mean carrier position and need no time-delay or relaxation mechanism to respond to the shifted carrier's position, in contrast to the usual Holstein and Davydov picture. The origin of the standard Debye-Waller renormalization is scrutinized using the Tokuyama-Mori theory including all the excited states of the oscillators and rigorous statements are made concerning its form. Limitations on the time interval of applicability of the semiclassical description resulting from the carrier dynamics are discussed.