Relations among theories of excitation transfer. II. Influence of spectral features on exciton motion

Abstract

The generalized-master-equation (GME) theory of excitation transfer is applied to the standard model of linearly interacting excitons and phonons, the spectral prescription for memory functions given by Kenkre and Knox is verified for the model, peculiarities of memory functions pertinent to isolated versus open systems are analyzed, and exciton transport relevant to representative memory functions is studied. Physical relations are established between the GME theory and the stochastic-Liouville-equation theories, thus completing the author's earlier formal study of these relations. The influence of spectral features on exciton motion is analyzed in detail and it is shown that the presence of zero-phonon peaks in optical spectra is an indication of long-time coherence in exciton motion. Criteria for the validity of theories in the context of a given real system are developed on the basis of the spectral analysis.