How Accurately Can Extended X-ray Absorption Spectra Be Predicted from First Principles? Implications for Modeling the Oxygen-Evolving Complex in Photosystem II.

Autor:	Beckwith MA; Max Planck Institute for Chemical Energy Conversion , Stiftstraße 34-36, D-45470 Mülheim an der Ruhr, Germany.; Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States., Ames W; Max Planck Institute for Chemical Energy Conversion , Stiftstraße 34-36, D-45470 Mülheim an der Ruhr, Germany., Vila FD; Department of Physics, University of Washington , Seattle, Washington 98195, United States., Krewald V; Max Planck Institute for Chemical Energy Conversion , Stiftstraße 34-36, D-45470 Mülheim an der Ruhr, Germany., Pantazis DA; Max Planck Institute for Chemical Energy Conversion , Stiftstraße 34-36, D-45470 Mülheim an der Ruhr, Germany., Mantel C; Département de Chimie Moléculaire, Université Joseph Fourier Grenoble, CNRS , F-38000 Grenoble, France., Pécaut J; Laboratoire de Reconnaissance Ionique et Chimie de Coordination, Service de Chimie Inorganique et Biologique, (UMR E-3 CEA/UJF, FRE3200 CNRS), CEA-Grenoble, INAC , 17 rue des Martyrs 38054 Grenoble cedex 9, France., Gennari M; Département de Chimie Moléculaire, Université Joseph Fourier Grenoble, CNRS , F-38000 Grenoble, France., Duboc C; Département de Chimie Moléculaire, Université Joseph Fourier Grenoble, CNRS , F-38000 Grenoble, France., Collomb MN; Département de Chimie Moléculaire, Université Joseph Fourier Grenoble, CNRS , F-38000 Grenoble, France., Yano J; Physical Biosciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States., Rehr JJ; Department of Physics, University of Washington , Seattle, Washington 98195, United States., Neese F; Max Planck Institute for Chemical Energy Conversion , Stiftstraße 34-36, D-45470 Mülheim an der Ruhr, Germany., DeBeer S; Max Planck Institute for Chemical Energy Conversion , Stiftstraße 34-36, D-45470 Mülheim an der Ruhr, Germany.; Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States.
Jazyk:	angličtina
Zdroj:	Journal of the American Chemical Society [J Am Chem Soc] 2015 Oct 14; Vol. 137 (40), pp. 12815-34. Date of Electronic Publication: 2015 Sep 29.
DOI:	10.1021/jacs.5b00783
Abstrakt:	First principle calculations of extended X-ray absorption fine structure (EXAFS) data have seen widespread use in bioinorganic chemistry, perhaps most notably for modeling the Mn4Ca site in the oxygen evolving complex (OEC) of photosystem II (PSII). The logic implied by the calculations rests on the assumption that it is possible to a priori predict an accurate EXAFS spectrum provided that the underlying geometric structure is correct. The present study investigates the extent to which this is possible using state of the art EXAFS theory. The FEFF program is used to evaluate the ability of a multiple scattering-based approach to directly calculate the EXAFS spectrum of crystallographically defined model complexes. The results of these parameter free predictions are compared with the more traditional approach of fitting FEFF calculated spectra to experimental data. A series of seven crystallographically characterized Mn monomers and dimers is used as a test set. The largest deviations between the FEFF calculated EXAFS spectra and the experimental EXAFS spectra arise from the amplitudes. The amplitude errors result from a combination of errors in calculated S0(2) and Debye-Waller values as well as uncertainties in background subtraction. Additional errors may be attributed to structural parameters, particularly in cases where reliable high-resolution crystal structures are not available. Based on these investigations, the strengths and weaknesses of using first-principle EXAFS calculations as a predictive tool are discussed. We demonstrate that a range of DFT optimized structures of the OEC may all be considered consistent with experimental EXAFS data and that caution must be exercised when using EXAFS data to obtain topological arrangements of complex clusters.
Databáze:	MEDLINE
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