Thomas-Fermi金属中的感应电荷：来自分子模拟的洞见
Induced charges in a Thomas-Fermi metal: insights from molecular simulations
AI总结：
本研究通过原子级分子模拟探究真空中离子在Thomas-Fermi金属中的感应电荷，对比连续介质静电学预测，验证了早期解析结论并明确了适用条件与近似方法。
摘要：
我们采用恒电势分子动力学模拟中的原子级描述方法，研究了真空中离子在Thomas-Fermi金属中诱导产生的电荷，并将结果与连续介质静电学的预测进行了对比。具体而言，我们探究了Thomas-Fermi屏蔽长度$l_{TF}$以及离子相对于表面的位置$d$对石墨电极中感应电荷分布的影响。当$d$和$l_{TF}$大于电极内部的原子间距时，连续介质预测能够捕捉到原子级描述观测到的大部分特征（石墨晶格原子位点导致的振荡除外）。在距离子径向距离较大的区域，有限$l_{TF}$的情况可以通过使用有效距离$d+l_{TF}$的理想金属解得到很好的近似。这需要为连续介质描述仔细定义金属与真空之间的有效界面。我们的原子级结果尤其支持了一项早期的解析预测[Vorotyntsev和Kornyshev，《Zh. Eksp. Teor. Fiz.》，1980年，78(3)，1008]，该预测针对Thomas-Fermi金属与可极化介质界面处的单个电荷，这一结论仍需在含显式溶剂的原子模拟中进行验证。
英文摘要：
We study the charge induced in a Thomas-Fermi metal by an ion in vacuum, using an atomistic description employed in constant-potential molecular dynamics simulations, and compare the results with the predictions from continuum electrostatics. Specifically, we investigate the effects of the Thomas-Fermi screening length $l_{TF}$ and the position $d$ of the ion with respect to the surface on the induced charge distribution in a graphite electrode. The continuum predictions capture most of the features observed with the atomistic description (except the oscillations due to the atomic sites of the graphite lattice), provided that $d$ and $l_{TF}$ are larger than the inter-atomic distances within the electrode. At large radial distance from the ion, the finite $l_{TF}$ case can be well approximated by the solution for a perfect metal using an effective distance $d+l_{TF}$. This requires a careful definition of the effective interface between the metal and vacuum for the continuum description. Our atomistic results support in particular an early analytical prediction [Vorotyntsev and Kornyshev, Zh. Eksp. Teor. Fiz., 1980, 78(3), 1008] for a single charge at the interface between a Thomas-Fermi metal and a polarizable medium, which remains to be tested in atomistic simulations with an explicit solvent.
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