铁硫蛋白活性中心铁硫簇的对称性破缺密度泛函 计算

应用密度泛函方法(DFT)计算了铁硫金属蛋白中的铁硫簇Fe~2S~2(SCH~3)~4]^2^-，Fe~3S~4(SCH~3)~3]^2^-以及Fe~4S~4(SCH~3)~4]^2^-的几何参数和磁偶合性质。采用对称性破缺态(BS)来描述Fe－Fe自旋偶合。计算结果表明：采用高自旋态(HS)计算的Fe－Fe间距与实验值有较大偏差，而由BS方法所计算的Fe－Fe间距与晶体结构测定数据相吻合。根据HS态和BS态的能量，计算了体系的海森堡偶合参数J，计算结果也较为接近实验估算值。

Calculation of iron-sulfur clusters in FeS protein active sites by broken symmetry density functional method

Density functional theory (DFT) has been used to calculate geometies and magnetic properties of iron - sulfur clusters Fe2S2(SCH3)4]2-, Fe3S4(SCH3)3]2- and Fe4S4(SCH3)4]2- in the active sites of FeS proteins. The Fe-Fe spin coupling is described by a broken symmetry (BS) state. The calculations show that the Fe-Fe distances obtained from high spin state (HS) are deviated from the experimental values significantly, whereas the Fe-Fe distances obtained by BS method are in good agreement with crystal structure data. Based on the energies of HS and BS states, Heisenberg coupling constant J of these clusters can be estimated and the calculated J values compare fairly well with the experimental data.