(Fig.1 Structural sketch of Mn4Ca cluster and the respective spin/redox for each studied state are shown in the left panel. In the right panels are shown the residues included in the QM region for all the QM/MM simulations. )
ABSTRACT:
Vibrational spectroscopy serves as a powerful tool for characterizing intermediate states within the Kok–Joliot cycle. In this study, we employ a QM/MM molecular dynamics framework to calculate the room temperature infrared absorption spectra of the S1, S2, and S3 states via the Fourier transform of the dipole time auto-correlation function. To better analyze the computational data and assign spectral peaks, we introduce an approach based on dipole–dipole correlation function of cluster moieties of the reaction center. Our analysis reveals variation in the infrared signature of the Mn4Ca cluster along the Kok–Joliot cycle, attributed to its increasing symmetry and rigidity resulting from the rising oxidation state of the Mn ions. Furthermore, we successfully assign the debated contributions in the frequency range around 600 cm−1. This computational methodology provides valuable insights for deciphering experimental infrared spectra and understanding the water oxidation process in both biological and artificial systems.
Authors: Capone Matteo, Parisse Gianluca, Narzi Daniele, Guidoni Leonardo
Publication date: 19 Jul 2024
Journal: Physical Chemistry Chemical Physics 2024
DOI (full article): https://doi.org/10.1039/D4CP01307G