Hyperfine tensors for a model system for the oxygen evolving complex of photosystem II: calculation of the anisotropy shift that occurs beyond the strong exchange limit

2019 ◽  
Vol 21 (41) ◽  
pp. 22902-22909
Author(s):  
Christine Mehlich ◽  
Christoph van Wüllen
Keyword(s):  
Photosystem Ii ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Mixed Valence ◽  
Model System ◽  
Manganese Complex ◽  
Broken Symmetry ◽  
Oxygen Evolving Complex ◽  
Strong Exchange ◽  
Oxygen Evolving

Broken-symmetry density functional calculations have been used to calculate effective 55Mn hyperfine (A) tensors for a mixed-valence tetranuclear manganese complex, a model system for the S2 state of the oxygen-evolving complex of photosystem II.

scholarly journals Simulation of the isotropic EXAFS spectra for the S2 and S3 structures of the oxygen evolving complex in photosystem II

2015 ◽  
Vol 112 (13) ◽  
pp. 3979-3984 ◽  
Author(s):  
Xichen Li ◽  
Per E. M. Siegbahn ◽  
Ulf Ryde
Keyword(s):  
Photosystem Ii ◽  
Water Oxidation ◽  
Density Functional ◽  
Structural Changes ◽  
Complete Agreement ◽  
Oxygen Evolving Complex ◽  
Chemical Modeling ◽  
Oxygen Evolving ◽  
High Degree ◽  
Exafs Spectra

Most of the main features of water oxidation in photosystem II are now well understood, including the mechanism for O–O bond formation. For the intermediate S2 and S3 structures there is also nearly complete agreement between quantum chemical modeling and experiments. Given the present high degree of consensus for these structures, it is of high interest to go back to previous suggestions concerning what happens in the S2–S3 transition. Analyses of extended X-ray adsorption fine structure (EXAFS) experiments have indicated relatively large structural changes in this transition, with changes of distances sometimes larger than 0.3 Å and a change of topology. In contrast, our previous density functional theory (DFT)(B3LYP) calculations on a cluster model showed very small changes, less than 0.1 Å. It is here found that the DFT structures are also consistent with the EXAFS spectra for the S2 and S3 states within normal errors of DFT. The analysis suggests that there are severe problems in interpreting EXAFS spectra for these complicated systems.

Generalized approximate spin projection calculations of effective exchange integrals of the CaMn4O5 cluster in the S1 and S3 states of the oxygen evolving complex of photosystem II

2014 ◽  
Vol 16 (24) ◽  
pp. 11911-11923 ◽  
Author(s):  
H. Isobe ◽  
M. Shoji ◽  
S. Yamanaka ◽  
H. Mino ◽  
Y. Umena ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Symmetry Breaking ◽  
Oxygen Evolution ◽  
Broken Symmetry ◽  
Spin Projection ◽  
Oxygen Evolving Complex ◽  
Structural Symmetry ◽  
Effective Exchange ◽  
The Right ◽  
Oxygen Evolving

Broken-symmetry UB3LYP calculations have elucidated structural symmetry-breaking in the S1 and S3 states of the oxygen evolution complex (OEC) of photosystem II (PSII), providing the right (RO)- and left (LO)-opened structures.

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