Charge localization in a diamine cation provides a test of energy functionals and self-interaction correction.
Charge localization in a diamine cation provides a test of energy functionals and self-interaction correction.
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二聚体阳离子中的电荷定位提供了能量功能和自我交互校正的测试。
DOI：
10.1038/ncomms11013
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发表时间：
2016-03-16
影响因子：
16.6
通讯作者：
Weber PM
中科院分区：
文献类型：
--
作者：
Cheng X;Zhang Y;Jónsson E;Jónsson H;Weber PM
密度泛函理论（DFT）在分子和材料的计算中有着广泛的应用。然而，它遭受了一个众所周知的过度强调电荷离域所产生的自相互作用的错误，不稳定的本地化状态。本文以对称二胺N，N′-二甲基哌嗪为模型，通过实验测定了两个氮原子中的一个氮原子上带正电荷的态和两个氮原子上带离域的正电荷的态的相对能量。发现电荷定域态的能量比电荷离域态高0.33（0.04）eV。这为电子结构计算的理论方法提供了一个重要的测试。计算与所有DFT泛函今天常用的，包括混合泛函与确切的交换，无法预测一个稳定的电荷局域化状态。然而，一个明确的自相互作用修正的应用程序的半本地功能识别两个状态，并给出了与实验和CCSD（T）计算非常一致的相对能量。 密度泛函理论在整个化学科学中被广泛使用，但过于强调电荷离域。在这里，作者通过实验探测了二胺阳离子的两种状态的能量，并展示了自相互作用校正如何允许准确预测这两种状态。
Density functional theory (DFT) is widely applied in calculations of molecules and materials. Yet, it suffers from a well-known over-emphasis on charge delocalization arising from self-interaction error that destabilizes localized states. Here, using the symmetric diamine N,N′-dimethylpiperazine as a model, we have experimentally determined the relative energy of a state with positive charge localized on one of the two nitrogen atoms, and a state with positive charge delocalized over both nitrogen atoms. The charge-localized state was found to be 0.33 (0.04) eV higher in energy than the charge-delocalized state. This provides an important test of theoretical approaches to electronic structure calculations. Calculations with all DFT functionals commonly used today, including hybrid functionals with exact exchange, fail to predict a stable charge-localized state. However, the application of an explicit self-interaction correction to a semi-local functional identifies both states and gives relative energy in excellent agreement with both experiment and CCSD(T) calculations. Density functional theory is widely used throughout the chemical sciences, but suffers from over-emphasis on charge delocalisation. Here, the authors experimentally probe the energies of two states of a diamine cation and show how a self-interaction correction allows for the accurate prediction of both states.