Nonlinear and stochastic modelling of energy transfer in Scheibe aggregates

The oxacyanine Scheibe aggregate is modelled by a two-dimensional cubic nonlinear Schrödinger equation with multiplicative noise, accounting for thermal fluctuations. For a possible choice of the physical parameters collapse of the initial state representing the Möbius-Kuhn coherent exciton may occur. The collapse time then increases with temperature. From experimental observations Möbius and Kuhn find a lifetime of the exciton which also increases with temperature. We finally consider soliton motion close to an impurity representing the acceptor molecule in the Scheibe aggregate.