论文标题
盐诱导的介电降低的显式溶剂理论
Explicit Solvent Theory of Salt-Induced Dielectric Decrement
论文作者
论文摘要
我们引入了一个场理论电解质模型，该模型由结构化溶剂分子和盐离子组成，并通过静电和硬核相互作用耦合。在这种明确的溶剂理论中，我们表征了盐驱动的电介质减小，而不是弱偶联（WC）静电。通过病毒膨胀来治疗盐电荷，可以放松先前形式主义的WC近似。这种病毒方法可以显式地包含多体盐溶剂相互作用，并直接导致通过添加稀盐的实验观察到的电解质介电常数的线性衰变。从我们的方法中出现的介电常数表明，溶剂介电常数的降低是通过抑制溶剂介电响应的极化电荷的盐筛选引起的。与实验相比，我们还表明，盐穿的介电常数公式可以同样地重现电解质介电常数的衰减，而温度升高，介电降低的热衰减以及其随盐量的增强。我们理论与这种广泛的实验趋势的一致定性一致性指出，静电离子 - 溶剂相关性是盐诱导的介电降低背后的主要机制。
We introduce a field-theoretic electrolyte model composed of structured solvent molecules and salt ions coupled by electrostatic and hard-core interactions. Within this explicit solvent theory, we characterize the salt-driven dielectric decrement beyond weak-coupling (WC) electrostatics. The WC approximation of prior formalisms is relaxed by treating the salt charges via a virial expansion. This virial approach enables the explicit inclusion of the many-body salt-solvent interactions, and directly leads to the experimentally observed linear decay of the electrolyte permittivity with added dilute salt. The permittivity formula emerging from our approach indicates that the reduction of the solvent permittivity is induced by the salt screening of the polarization charges suppressing the dielectric response of the solvent. By comparison with experiments, we also show that the salt-dressed permittivity formula can equally reproduce the attenuation of the electrolyte permittivity with rising temperature, the thermal decay of the dielectric decrement, and its intensification with the salt valency. The consistent qualitative agreement of our theory with this wide range of experimental trends points out the electrostatic ion-solvent correlations as the primary mechanism behind the salt-induced dielectric decrement.
