Agenda

Résumé : I will introduce the advantage of multi-scale modelling strategies and present some examples where we have successfully applied them to model different kinds of properties and processes in molecular materials. I will then focus on presenting an application to Resonance Energy Transfer (RET). In this process, the energy is transferred from an excited molecule, called the energy donor (D), to an acceptor molecule (A). We have investigated Förster RET for a pair of dyes linked to a calixarene scaffold. In such systems the relative orientation of the D and A changes on a time-scale comparable to RET dynamics, making the two two limiting regimes, static and dynamic, hardly applicable. In the advanced multiscale approach to the dynamics of RET, we combine DFT and TD-DFT results on the energy donor (D) and acceptor (A) moieties with an extensive equilibrium and non-equilibrium molecular dynamics (MD) analysis of a bound D–A pair in solution to build a coarse-grained kinetic model. We demonstrate that a thorough MD study is needed to properly address RET: the enormous configuration space visited by the system cannot be reliably sampled accounting only for a few representative configurations. Moreover, the conformational motion of the RET pair, occurring in a similar time scale as the RET process itself, leads to a sizable increase of the overall process efficiency.