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首页> 外文期刊>Chemphyschem: A European journal of chemical physics and physical chemistry >Assessment of density functionals for the high-spin/low-spin energy difference in the low-spin iron(II) tris(2,2 '-bipyridine) complex
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Assessment of density functionals for the high-spin/low-spin energy difference in the low-spin iron(II) tris(2,2 '-bipyridine) complex

机译：评估低旋铁（II）三（2,2'-联吡啶）络合物中高旋/低旋能量差的密度泛函

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摘要

In the iron(II) low-spin complex [Fe(bpy)(3)](2+), the zero-point energy difference between the T-5(2g)(t(2g)(4)e(g)(2)) high-spin and the (1)A(1g)(t(2g)(6)) low-spin states, Delta E-HL(0), is estimated to lie in the range of 2500-5000 cm(-1). This estimate is based on the low-temperature dynamics of the high-spin -> low-spin relaxation following the light-induced population of the high-spin state and on the assumption that the bond-length difference between the two states Delta r(HL) is equal to the average value of approximate to 0.2 angstrom, as found experimentally for the spin-crossover system. Calculations based on density functional theory (DFT) validate the structural assumption insofar as the low-spin-state optimised geometries are found to be in very good agreement with the experimental X-ray structure of the complex and the predicted high-spin geometries are all very close to one another for a whole series of common GGA (PB86, PW91, PBE, RPBE) and hybrid (BAYP B3LYP*, PBE1PBE) functionals. This confirmation of the structural assumption underlying the estimation of Delta E-HL(0) from experimental relaxation rate constants permits us to use this value to assess the ability of the density functionals for the calculation of the energy difference between the HS and LS states. Since the different functionals give values from -1000 to 12000 cm(-1), the comparison of the calculated values with the experimental estimate thus provides a stringent criterion for the performance of a given functional. Based on this comparison the RPBE and B3LYP* functionals give the best agreement with experiment.
机译：在铁（II）低自旋络合物[Fe（bpy）（3）]（2+）中，T-5（2g）（t（2g）（4）e（g）之间的零点能量差（2）高旋转状态和（1）A（1g）（t（2g）（6））低旋转状态Delta E-HL（0）估计在2500-5000 cm范围内（-1）。该估计是基于光诱导的高自旋态种群之后高自旋->低自旋弛豫的低温动力学，以及两个状态之间的键长差Δr（ HL）等于大约0.2埃的平均值，这是自旋交叉系统的实验结果。只要发现低自旋态优化的几何结构与配合物的实验X射线结构非常吻合，并且预测的高自旋几何结构全部符合密度泛函理论（DFT）的计算，就可以验证结构假设。整个通用GGA系列（PB86，PW91，PBE，RPBE）和混合功能（BAYP B3LYP *，PBE1PBE）彼此非常接近。对根据实验弛豫速率常数估算Delta E-HL（0）的结构假设的这种确认，使我们能够使用此值来评估密度泛函计算HS和LS状态之间的能量差的能力。由于不同的功能给出的值从-1000到12000 cm（-1），因此将计算值与实验估计值进行比较，从而为给定功能的性能提供了严格的标准。基于此比较，RPBE和B3LYP *功能与实验具有最佳一致性。

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