Modeling radiative and non-radiative pathways at both the Franck–Condon and Herzberg–Teller approximation level

Here, we present a concise model that can predict the photoluminescent properties of given compound from first principles, both within and beyond Franck–Condon approximation. The formalism required to compute fluorescence, Internal Conversion (IC), Inter-System Crossing (ISC) is discussed. IC mechanism, in particular, difficult pathway due difficulties associated with computation bosonic configurations non-adiabatic coupling elements. offer discussion breakdown on how these pathways at Density Functional Theory (DFT) level respect its computational implementation, strengths, current limitations. then used quantum yield (PLQY) number small but important compounds: anthracene, tetracene, pentacene, diketo-pyrrolo-pyrrole (DPP), Perylene Diimide (PDI) polarizable continuum model. Rate constants for IC, ISC compare well most part experiment, despite triplet energies being overestimated degree. resulting PLQYs are promising theory DFT. While obtained positive result PDI limit, other systems require second order correction. Recomputing yields Herzberg–Teller terms 0.19, 0.08, 0.04, 0.70, 0.99 DPP, PDI, respectively. Based results, confident presented methodology sound chemistry presents an stepping stone search tool larger coupled systems.