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

Area of Science:

• Quantum biology
• Photochemistry
• Biophysics

Background:

• The role of quantum coherence in efficient electronic excitation transport (EET) within light-harvesting complexes is debated.
• A prior study proposed an incoherent Born-Markov (incoherent BM) rate model for a three-site system, omitting intersite coherence.

Purpose of the Study:

• Generalize the incoherent BM rate model to arbitrary N-site systems.
• Compare the computational efficiency and accuracy of the incoherent BM model against secular Redfield theory.
• Assess coherence effects in well-studied light-harvesting complexes.

Main Methods:

• Generalization of the incoherent Born-Markov rate model for N-site systems.
• Comparison with secular Redfield theory within the Lindbladian formalism.
• Application to light-harvesting II (LHII)-type trimer and Fenna-Matthews-Olson (FMO) complex models.

Main Results:

• The generalized incoherent BM model demonstrates computational efficiency compared to the Lindbladian master equation.
• Coherence effects were assessed in LHII and FMO complexes under Born-Markov approximation.
• The incoherent BM model is computationally advantageous for large systems.

Conclusions:

• The incoherent Born-Markov rate model provides a computationally efficient approach for studying EET.
• This model is suitable for optimization studies in complex multisite excitonic systems, especially when coherence effects are negligible.