Congratulations to our PhD student Piermarco Saraceno for his publication titled “Quantum Dynamics Simulations Reveal Ultrafast and Coherent Charge Transfer in the Lhca4 Antenna of Photosystem I” in The Journal of Physical Chemistry Letters.
This work investigates the molecular origin of the low-energy “red forms” in the Lhca4 light-harvesting antenna of Photosystem I, which play a key role in regulating energy flow in plant photosynthesis. The study combines first-principles QM/MM-based Hamiltonians with advanced quantum dynamics simulations using the ML-MCTDH approach to get insight into the ultrafast excited-state dynamics in the a603–a609 chlorophyll dimer. The simulations reveal an ultrafast (~50 fs) and coherent population transfer from locally excited states to a charge-transfer state, strongly modulated by the protein environment through the exciton–CT energy gap. The results demonstrate that the red state of Lhca4 is a coherent exciton–charge-transfer mixture with partial charge separation, capable of maintaining bright emission and supporting energy transfer. These findings provide new mechanistic insight into the origin of red forms in Photosystem I and highlight the role of coherent charge-transfer processes in tuning the functionality of natural light-harvesting complexes.
The paper is available at the following link: https://doi.org/10.1021/acs.jpclett.5c02463
