arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2008.03840cond-mat.softcond-mat.stat-mechphysics.chem-ph
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电解质理论,包括空间,吸引和水合作用

Theory of electrolytes including steric, attractive, and hydration interactions

Ryuichi Okamoto, Kenichiro Koga, Akira Onuki

摘要:

我们提出了一个连续介质理论的电解质组成的水状溶剂和单价离子。首先,我们开始与密度泛函$\cal F$的粗粒度的溶剂,阳离子和阴离子的密度,包括Debye-Hückel自由能,库仑相互作用,和这三个组件之间的直接相互作用。这些密度波动服从分布$\propto \exp(- {\cal F}/k_BT)$。通过消除$\cal F$中的溶剂密度偏差,得到了离子间的有效非库仑相互作用,包括直接作用和溶剂介导作用。%,其中后者以离子体积%表示,并且与溶剂可压缩性成反比。然后,我们推导出一般表达式的离子相关性,表观分体积,和活性和渗透系数的线性顺序的平均盐密度$n_{\rm s}$。其次,我们使用Mansoori-Carnahan-Starling-Leland模型$[$ J. Chem. Phys. { \bf 54},1523(1971)$]$对三组分硬球进行了数值分析。有效的相互作用敏感地依赖于阳离子和阴离子的大小,由于空间和水合作用之间的竞争,这是小-大离子对之间的排斥和对称对之间的吸引力。这与以前的实验和柯林斯的规则$[$生物物理学。J. { \bf 72},65(1997)$]$ .我们还给出了简单的近似表达式的离子相互作用系数适用于任何离子的大小。

英文摘要:

We present a continuum theory of electrolytes composed of a waterlike solvent and univalent ions. First, we start with a density functional $\cal F$ for the coarse-grained solvent, cation, and anion densities, including the Debye-Hückel free energy, the Coulombic interaction, and the direct interactions among these three components. These densities fluctuate obeying the distribution $\propto \exp(- {\cal F}/k_BT)$. Eliminating the solvent density deviation in $\cal F$, we obtain the effective non-Coulombic interactions among the ions, which consist of the direct ones and the solvent-mediated ones. %where the latter are written in terms of the ion volumes %and are inversely proportional to the solvent compressibility. We then derive general expressions for the ion correlation, the apparent partial volume, and the activity and osmotic coefficients up to linear order in the average salt density $n_{\rm s}$. Secondly, we perform numerical analysis using the Mansoori-Carnahan-Starling-Leland model $[$J. Chem. Phys. {\bf 54}, 1523 (1971)$]$ for three-component hardspheres. The effective interactions sensitively depend on the cation and anion sizes due to competition between the steric and hydration effects, which are repulsive between small-large ion pairs and attractive between symmetric pairs. These agree with previous experiments and Collins' rule $[$Biophys. J. {\bf 72}, 65 (1997)$]$. We also give simple approximate expressions for the ionic interaction coefficients valid for any ion sizes.

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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