2026-04-17T10:44:15Zhttps://recercat.cat/oai/request

oai:recercat.cat:2445/1756142025-12-05T14:12:37Zcom_2072_1057col_2072_478815col_2072_478917

00925njm 22002777a 4500 dc Rosnik, Andreana M. R author Curutchet Barat, Carles E. author 2021-03-23T10:38:17Z 2021-03-23T10:38:17Z 2015-12-08 2021-03-23T10:38:18Z Over the past decade, both experimentalists and theorists have worked to develop methods to describe pigment-protein coupling in photosynthetic light-harvesting complexes in order to understand the molecular basis of quantum coherence effects observed in photosynthesis. Here we present an improved strategy based on the combination of quantum mechanics/molecular mechanics (QM/MM) molecular dynamics (MD) simulations and excited-state calculations to predict the spectral density of electronic-vibrational coupling. We study the water-soluble chlorophyll-binding protein (WSCP) reconstituted with Chl a or Chl b pigments as the system of interest and compare our work with data obtained by Pieper and co-workers from differential fluorescence line-narrowing spectra (Pieper et al. J. Phys. Chem. B 2011, 115 (14), 4042−4052). Our results demonstrate that the use of QM/MM MD simulations where the nuclear positions are still propagated at the classical level leads to a striking improvement of the predicted spectral densities in the middle- and high-frequency regions, where they nearly reach quantitative accuracy. This demonstrates that the so-called 'geometry mismatch' problem related to the use of low-quality structures in QM calculations, not the quantum features of pigments high-frequency motions, causes the failure of previous studies relying on similar protocols. Thus, this work paves the way toward quantitative predictions of pigment-protein coupling and the comprehension of quantum coherence effects in photosynthesis. Llum Fotosíntesi Química quàntica Química física Light Photosynthesis Quantum chemistry Physical and theoretical chemistry Theoretical characterization of the spectral density of the water-soluble chlorophyll-binding protein from combined quantum mechanics/molecular mechanics molecular dynamics simulations