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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Calculation of the EPR g-Tensors of High-Spin Radicals with Density Functional Theory
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Calculation of the EPR g-Tensors of High-Spin Radicals with Density Functional Theory

机译:用密度泛函理论计算高自旋自由基的EPR g-张量

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The second-order DFT approach of Schreckenbach and Ziegler to the computation of EPR g tensors of doublet radicals (J. Phys. Chem. A 1997, 101, 3388), has been generalized to arbitrary spatially nondegenerate electronic states. The new technique is applied to a large number (47) of diatomic main-group radicals, in ~n#SIGMA# (n > 2) ground states. Calculated principal components, of the EPR g tensors, are in a good agreement with experiment for main group radicals, with the average errors approaching the accuracy available in experimental matrix isolation studies (VWN average absolute error: 3.8 ppt). The agreement with experiment deteriorates for the mixed, main group-transition metal radicals (VWN error: 8.1 ppt) but the major trends in #DELTA#g perpendicular values are still reproduced. The approach largely breaks down for radicals containing chemical bonds between two transition metal atoms (VWN error: 30 ppt). In all cases, the calculated g tensors are insensitive to the choice of the approximate exchange-correlation functional, with the simple VWN LDA, and gradient-corrected BP86 and RPBE functionals, giving essentially identical results. As an example of the possible future applications of the technique, we examine the g-tensor of the first ~3B_u excited state of the trans-(CNSSS)_2~(2+) cation. Our calculations for this systems agree well with the experimental results, both for the magnitudes, and for the orientations of the principal components.
机译:Schreckenbach和Ziegler的二阶DFT方法用于计算双峰基团的EPR g张量(J. Phys。Chem。A 1997,101,3388),已推广到任意空间非简并电子态。这项新技术应用于〜n#SIGMA#(n> 2)基态的大量(47)双原子主基团。 EPR g张量的计算主成分与主基团的实验非常吻合,平均误差接近实验矩阵隔离研究中可用的准确性(VWN平均绝对误差:3.8 ppt)。对于混合的,主要的基团过渡金属自由基(VWN误差:8.1 ppt),与实验的一致性下降,但仍再现了#DELTA#g垂直值的主要趋势。对于包含两个过渡金属原子之间的化学键的自由基,该方法大为分解(VWN误差:30 ppt)。在所有情况下,通过简单的VWN LDA以及经过梯度校正的BP86和RPBE函数,所计算的g张量对近似交换相关函数的选择都不敏感,从而得到基本相同的结果。作为该技术未来可能应用的一个例子,我们研究了反式-(CNSSS)_2〜(2+)阳离子的第一个〜3B_u激发态的g张量。我们对该系统的计算结果与实验结果非常吻合,无论是在量值上还是在主成分的方向上。

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