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建立了S_2态光合释氧络合物(OEC)的原子-键电负性均衡模型(ABEEMσπ)的电荷参数,并使用ABEEM/MM/MD可极化力场的分子动力学模拟和对称性破损的DFT研究了光合作用制造氧气的微观机制.HF/STO-3G(采用此基组的原因请见引用文献)水平下的电荷拟合结果证明了ABEEMσπ模型计算电荷分布的合理性和高效性.MD模拟显示,S_2态Mn_4CaO_5的双向异构化过程伴随Ca上的水分子W3转移至Mn1(Ⅲ)/Mn_4(Ⅲ),它很可能作为底物水之一,与O_5在S4态结合产生O_2.基于此,考察了全自旋态下两种异构体形式中O-O键形成的自由基耦合机理.BS-DFT计算结果表明,开立方结构的释氧活性大大优于闭立方结构,金属锰和氧自由基的自旋耦合方式也是反应性的决定性因素,同时,OEC的结构灵活性对于S态循环和光合水分解至关重要.
The charge parameters of the atom - bond electronegativity equilibrium model (SABE) of S_2 OEC were established and the molecular dynamics simulation and symmetry damage of the polarized field of ABEEM / MM / MD DFT studied the microscopic mechanism of photosynthesis in the production of oxygen.HF / STO-3G (For a rationale of this basis, see the citations) The charge-fitting results at the level demonstrate the rationality and efficiency of the ABEEMσπ model in calculating the charge distribution. MD simulation shows that the bidirectional isomerization process of Mn_4CaO_5 in S_2 state is accompanied by the transfer of W3 to Mn1 (Ⅲ) / Mn_4 (Ⅲ) from water molecule Ca in Ca2 +, which is probably one of substrate water and combines with O_5 in S4 state to produce O2 Based on this, the mechanism of radical coupling between OO bonds in two isomeric forms under full spin state is investigated.The results of BS-DFT show that the oxygen evolution activity of open cubic structure is much better than that of closed cubic structure, The spin coupling with oxygen radicals is also a decisive factor in reactivity, and at the same time, the structural flexibility of OEC is crucial for S-state cycling and photosynthetic water dissociation.