Energy transfer in structured and unstructured environments: Master equations beyond the Born-Markov approximations

Area of Science:

• Quantum dynamics
• Chemical physics
• Spectroscopy

Background:

• Excitonic energy transfer is fundamental in molecular systems.
• Standard models often rely on Born-Markov approximations, neglecting system-environment correlations.
• Understanding non-Markovian effects is key for accurate predictions.

Purpose of the Study:

• To explore excitonic energy transfer dynamics in molecular dimers coupled to structured and unstructured environments.
• To extend the reaction coordinate master equation beyond Born-Markov approximations.
• To assess the validity of semiclassical approximations like the Zusman equations.

Main Methods:

• Extended reaction coordinate master equation technique.
• Incorporation of system-environment correlations and non-Markovian effects.
• Comparison with numerical hierarchical equations of motion and Zusman equations.

Main Results:

• Accurate energy transfer dynamics obtained for underdamped and overdamped environments, matching hierarchical equations of motion.
• Zusman equations shown to be inadequate for describing dynamics when Born-Markov approximations fail.
• Structured environments can enhance dimer energy transfer rates compared to unstructured ones.

Conclusions:

• Proper accounting for quantum correlations between system and environment is essential when Born-Markov approximations are invalid.
• The enhancement of energy transfer in structured environments is sensitive to resonance conditions and component strengths.
• The reaction coordinate formalism provides a robust framework for studying complex energy transfer dynamics.