Density-based Reactivity Theory Applied to Excited States

Excited states are essential to many chemical processes in photosynthesis, solar cells, light-emitting diodes, and so on, yet how to formulate, quantify, and predict physiochemical properties for excited states from the theoretical perspective is far from being established. In this work, we leverage the four density-based frameworks from density functional theory (DFT) including orbital-free DFT, conceptual DFT, information-theoretic approach and direct use of density associated descriptors and apply them to the lowest singlet and triplet excited states for a variety of molecular systems to examine their stability, bonding, and reactivity propensities. Our results from the present study elucidate that it is feasible to employ these density-based frameworks to appreciate physiochemical properties for excited states and that excited state propensities can be markedly different from, sometime completely opposite to, those in the ground state. This work is the first effort, to the best of our knowledge, utilizing density-based reactivity frameworks to excited state. It should offer ample opportunities in the future to deal with real-world problems in photophysical and photochemical processes and transformations.