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arXiv 1002.4117cond-mat.mtrl-sci
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自相互作用误差在第一性原理研究石墨烯化学吸附中的作用

Role of the self-interaction error in studying chemisorption on graphene from first-principles

Simone Casolo, Espen Flage-Larsen, Ole Martin Løvvik, George R. Darling, Gian Franco Tantardini

摘要:

气态物质,特别是氢原子在石墨烯上的吸附是该材料化学的重要过程。在平衡几何构型下,H原子共价键合到从表面平面中起皱的碳上。然而,当考虑完全粘附动力学时,\emph{flat}石墨烯几何形状变得重要。在这里,我们展示了GGA-DFT如何预测这种几何结构的错误自旋状态,即石墨烯上单个H原子的$S_z$ =0。我们展示了这是如何引起的自相互作用的错误,因为该系统显示分数电子职业的两个频带最接近的费米能量。它演示了如何使用混合泛函或GGA+ $U$方法可以用来检索正确的自旋解,虽然后者给出了一个不正确的势能曲线。

英文摘要:

Adsorption of gaseous species, and in particular of hydrogen atoms, on graphene is an important process for the chemistry of this material. At the equilibrium geometry, the H atom is covalently bonded to a carbon that puckers out from the surface plane. Nevertheless the \emph{flat} graphene geometry becomes important when considering the full sticking dynamics. Here we show how GGA-DFT predicts a wrong spin state for this geometry, namely $S_z$=0 for a single H atom on graphene. We show how this is caused by the self-interaction error since the system shows fractional electron occupations in the two bands closest to the Fermi energy. It is demonstrated how the use of hybrid functionals or the GGA+$U$ method an be used to retrieve the correct spin solution although the latter gives an incorrect potential energy curve.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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