On the origin of the electrostatic potential difference at a liquid-vacuum interface
On the origin of the electrostatic potential difference at a liquid-vacuum interface
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DOI：
10.1063/1.3027513
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发表时间：
2008-12-21
影响因子：
4.4
通讯作者：
Roux, Benoit
中科院分区：
文献类型：
--
作者：
Harder, Edward;Roux, Benoit
通过考虑靠近界面的分子的简单模型，通过计算机模拟计算得到界面势的微观来源。该模型假定分子具有各向同性取向，电荷密度为高斯分布。相对于气相，内部电荷密度更负的分子倾向于产生负的界面势，而内部电荷密度更正的分子则会产生正的界面势。将模型的界面势与非极性真空-甲烷系统和极性真空-水界面系统的分子动力学模拟计算的界面势进行了比较。通过分子动力学模拟计算得到真空-甲烷界面电位（-220 mV），该模型具有定量精度。对于真空-水界面系统，该模型预测电位为-400 mV，而分子动力学模拟结果为-510 mV。这种各向同性对界面势的贡献的物理意义是用液态甲烷离子溶剂化的例子来检验的。
The microscopic origin of the interface potential calculated from computer simulations is elucidated by considering a simple model of molecules near an interface. The model posits that molecules are isotropically oriented and their charge density is Gaussian distributed. Molecules that have a charge density that is more negative toward their interior tend to give rise to a negative interface potential relative to the gaseous phase, while charge densities more positive toward their interior give rise to a positive interface potential. The interface potential for the model is compared to the interface potential computed from molecular dynamics simulations of the nonpolar vacuum-methane system and the polar vacuum-water interface system. The computed vacuum-methane interface potential from a molecular dynamics simulation (-220 mV) is captured with quantitative precision by the model. For the vacuum-water interface system, the model predicts a potential of -400 mV compared to -510 mV, calculated from a molecular dynamics simulation. The physical implications of this isotropic contribution to the interface potential is examined using the example of ion solvation in liquid methane.