Abstract
General formulae for memory functions of a single molecular exciton in an initially unrelaxed periodic lattice are made explicit by partially resuming a perturbation series to infinity. The decay time of the memory functions determining the loss of coherence is estimated and it is shown that it may exceed the usual estimates obtained from optical data using the lowest-order Kenkre-Knox relations by several orders of magnitude. Hence, the exciton motion may remain coherent and insensitive to temperature over much longer intervals following the exciton creation than is usually assumed.

This publication has 15 references indexed in Scilit: