Artifacts due to trivial unavoided crossings in the modeling of photoinduced energy transfer dynamics in extended conjugated molecules

A previously developed algorithm to identify potential energy surface crossings involving interacting or noninteracting states during nonadiabatic excited-state molecular dynamics simulations, allows the diabatic pathway to be followed through the crossing region so that there is no experienced change in the states identity. In this Letter, we investigate the transition from interacting/delocalized states to noninteracting/localized states in oligomers of poly-phenylene vinylene separated by varying distances. We demonstrate that the appearance of trivial unavoided crossings during nonadiabatic dynamics leads to artifacts in the state population analysis. Consequently, changes in the localization of the electronic transition density must be followed instead.