Long-lived excitonic beatings in finite chains under adiabatic motion

Abstract We investigate transport of a Frenkel exciton in finite one-dimensional chains, where temperature induced interparticle vibrations dynamically modulate the electronic couplings between neighboring particles. In the adiabatic regime, where vibrational motion is slower than excitation transfer between sites, this modulation gives rise to long-lived oscillations in the exciton populations. These oscillations, which we refer to as adiabatic beatings, are most pronounced at the boundaries of the chain. The amplitude of these beatings decreases with increasing chain length and is larger for chains with an odd number of particles than for those with an even number. Furthermore, the beatings are even present for disorder strength smaller than the equilibrium interparticle coupling, although their amplitude decreases gradually and eventually vanishes when the disorder becomes comparable to the coupling strength.