ESTYMA · Excited state quantum dynamics in molecular aggregates: a unified description from biology to devices

The coherent dynamics of excitons in systems of biological interest and in organic materials can now be studied with advanced experimental techniques, including two dimensional electronic spectroscopy, with time resolution of few femtoseconds. The theory of open quantum systems, that should support the interpretation of these new experiments, has been developed in different contexts over the past 60 years but seems now very inadequate for the problems of current interest. First of all, the systems under investigation are extremely complex and the most common approach, based on the development of phenomenological models, is often not very informative. Many different models yield results in agreement with the experiments and there is no systematic way to derive these models or to select the best model among many. Secondly, the quantum dynamics of excitons is so fast that one cannot assume that the dynamics of environment is much faster than the dynamics of the system, an assumption crucial for most theories. A remedy to the current limitation is proposed here through the following research objectives.(1) A general and automatic protocol will be developed to generate simple treatable models of the system from an accurate atomistic description of the same system based on computational chemistry methods.(2) A professionally-written software will be developed to study the quantum dynamics of model Hamiltonians for excitons in molecular aggregates. This software will incorporate different methodologies and will be designed to be usable also by non-specialists in the theory of quantum open systems (e.g. spectroscopists, computational chemists).(3) A broad number of problems will be studied with this methodology including (i) exciton dynamics in light harvesting complexes and artificial proteins and (ii) exciton dynamics in molecular aggregates of relevance for organic electronics devices.