Une approche théorique à la photochimie moléculaire basées sur la densité pour l'étude de propriétés remarquables relatives aux états excités moléculaires

This thesis focuses on devising, constructing, and applying cost-effective approaches to calculate the photophysical propertiesof molecular systems in the context of time-dependent density functional theory (TDDFT). The objective of our workis to define a set of purposely-derived density descriptors that can be combined to provide a straightforward interpretationof the relevant photophysical pathways for the many processes taking place at the excited state. More specifically,we deliver a collection of TDDFT-based computational protocols, based on the knowledge of ground and excited statedensities, to characterize the excited-state potential energy surfaces of molecular systems. Overall, the state-trackingalgorithm and the density-descriptors outlined in this thesis collectively provide a reliable and cost-effective way of disclosingexcited state pathways within the theoretical modeling of photophysical processes. The proposed approach canbe computed "on the fly" to identify critical areas for TDDFT approaches while, contextually, providing a method for thequalitative identification - in conjunction with energy criteria - of possible reactions paths.Voire annexe description en englai