Like Charges Attract?

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• 作者：Tianshan Zhao ; Jian Zhou ; Qian Wang ; Puru Jena
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2016
• 出版时间：July 21, 2016
• 年：2016
• 卷：7
• 期：14
• 页码：2689-2695
• 全文大小：373K
• 年卷期：0
• ISSN：1948-7185

文摘

Using multiscale first-principles calculations, we show that two interacting negatively charged B₁₂I₉^– monoanions not only attract, in defiance of the Coulomb’s law, but also the energy barrier at 400 K is small enough that these two moieties combine to form a stable B₂₄I₁₈^2– moiety. Ab initio molecular dynamics simulations further confirm its stability up to 1500 K. Studies of other B₁₂X₉^– (X = Br, Cl, F, H, Au, CN) show that while all of these B₂₄X₁₈^2– moieties are stable against dissociation, the energy barrier, with the exception of B₂₄Au₁₈^2–, is large so as to hinder their experimental observation. Our results explain the recent experimental observation of the “spontaneous” formation of B₂₄I₁₈^2– in an ion trap. A simple model based upon electrostatics shows that this unusual behavior is due to competition between the attractive dipole–dipole interaction caused by the aspherical shape of the particle and the repulsive interaction between the like charges.