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DFT performance for the hole transfer parameters in DNA π stacks

机译:DNAπ堆中空穴转移参数的DFT性能

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Recently, we showed that unoccupied Kohn-Sham (KS) orbitals stemming from DFT calculations of a neutral system can be used to derive accurate estimates of the free energy and electronic couplings for excess electron transfer in DNA (Félix and Voityuk, J Phys Chem A 2008, 112, 9043). In this article, we consider the propagation of radical cation states (hole transfer) through DNA π-stacks and compare the performance of different exchange-correlation functionals to estimate the hole transfer (HT) parameters. Two different approaches are used: (1) calculations that use occupied KS orbitals of neutral π stacks of nucleobases, and (2) the time-dependent DFT method which is applied to the radical cation states of these stacks. Comparison of the calculated parameters with the reference data suggests that the best results are provided by the KS scheme with hybrid functionals (B3LYP, PBE0, and BH&HLYP). The TD DFT approach gives significantly less accurate values of the HT parameters. In agreement with high-level ab initio results, the KS scheme predicts that the hole in π stacks is confined to a single nucleobase; in contrast, the spin-unrestricted DFT method considerably overestimates the hole delocalization in the radical cations.
机译:最近,我们证明了源自中性系统DFT计算的空空的Kohn-Sham(KS)轨道可用于得出自由能和电子耦合的准确估计,以进行DNA中的过量电子转移(Félix和Voityuk,《物理学报》 A 2008,112,9043)。在本文中,我们考虑了自由基阳离子状态(空穴转移)在DNAπ堆栈中的传播,并比较了不同交换相关功能的性能,以估计空穴转移(HT)参数。使用两种不同的方法:(1)使用中性核碱基的π堆栈的占据KS轨道进行计算,以及(2)应用于这些堆栈的自由基阳离子状态的时变DFT方法。计算参数与参考数据的比较表明,具有混合功能(B3LYP,PBE0和BH&HLYP)的KS方案可提供最佳结果。 TD DFT方法给出的HT参数准确度大大降低。与高水平的从头算结果相一致,KS方案预测π堆栈中的孔被限制在单个核碱基内;相反,自旋无限制DFT方法大大高估了空穴在阳离子中的离域作用。

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