Analyzing Coherence Effects in Multisite Electronic Excitation Transport Using the Incoherent Born-Markov Rate Model

The role of quantum coherence in enabling efficient electronic excitation transport (EET) within light-harvesting complexes remains an open question. A recent study introduced an incoherent Born-Markov (incoherent BM) rate model for a three-site system by neglecting intersite coherence in the secular Redfield master equation. In this work, we generalize this approach to an arbitrary N-site system. To demonstrate its utility, we compare incoherent BM dynamics with secular Redfield theory in the Lindbladian formalism to assess coherence effects in two well-studied systems: the light-harvesting II (LHII)-type trimer and the seven-site Fenna-Matthews-Olson (FMO) complex, both within the Born-Markov approximation. Our results highlight the computational efficiency of the incoherent BM rate model relative to the Lindbladian master equation, making it particularly suitable for optimization studies in complex multisite excitonic systems where coherence effects may be negligible.