Abstract

In the field of photochemistry, the role of theoretical chemistry in designing new photoactive molecules is increasingly significant, driven by enhanced computational capabilities and the data science revolution. Consequently, grasping the mechanisms governing photochemistry is critical for effective theoretical molecular design. While nonadiabatic molecular dynamics is the technique of election for predicting photochemical outcomes, its computational demands can be substantial (especially in the context of proteins and fluorescent probes), often necessitating prior knowledge of the photochemistry under investigation. Can a “simpler” exploration of the intersection seam give us access to photochemical properties? Addressing this challenge, we present and discuss the Nonadiabatic Nanoreactor, a novel tool that extensively samples the intersection space between two electronic states via seam-constrained metadynamics to pinpoint key conical intersections and link them to accessible photoproducts. Additionally, we show that the energetical accessibility of conical intersections dictates brightness in fluorescent proteins, offering insights into the design of light-driven molecular systems.