We study the strong-coupling (SC) interaction between two like-charged membranes of finite thickness embedded in a medium of higher dielectric constant. A generalized SC theory is applied along with extensive Monte-Carlo simulations to study the image charge effects induced by multiple dielectric discontinuities in this system. These effects lead to strong counterion crowding in the central region of the inter-surface space upon increasing the solvent/membrane dielectric mismatch and change the membrane interactions from attractive to repulsive at small separations. These features agree quantitatively with the SC theory at elevated couplings or dielectric mismatch where the correlation hole around counterions is larger than the thickness of the central counterion layer.
The dielectric nature of polar liquids underpins much of their ability to act as useful solvents, but its description is complicated by the long-ranged nature of dipolar interactions. This is particularly pronounced under the periodic boundary conditions commonly used in molecular simulations. In this article, the dielectric properties of a water model whose intermolecular electrostatic interactions are entirely short-ranged are investigated. This is done within the framework of local molecular field theory (LMFT), which provides a well controlled mean-field treatment of long-ranged electrosta…
Electrostatic self-assembly of neutral particles on a dielectric substrate: A theoretical study via a multiple-image method and an effective-dipole approach
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 dilu…
We develop of a field-theoretic approach for the treatment of both the non-local and the non-linear response of structured liquid dielectrics. Our systems of interest are composed of dipolar solvent molecules and simple salt cations and anions. We describe them by two independent order parameters, the polarization field for the solvent and the charge density field for the ions, including and treating the non-electrostatic part of the interactions explicitly and consistently. We show how to derive functionals for the polarization and the electrostatic field of increasingly finer scales and solv…
Theoretical analysis of screened many-body electrostatic interactions between charged polarizable particles
本文基于Lindgren et al. J. Comp. Phys. 371,712-731(2018)和Quan et al. arXiv:1807.05384(2018)这两篇先前的论文,设计了一种新方法来解决由许多介电粒子组成的系统中的静电相互作用的计算问题,这些粒子嵌入均匀的介电介质中,而均匀的介电介质也可以被载流子渗透。该系统由每个粒子的电荷、大小、位置和介电常数以及介质的介电常数和德拜长度定义。考虑到粒子的介电性质的影响进行了探讨,在选定的情况下,在介质中的电解质的存在下,可以显着影响总的相互作用。将系统中所有粒子之间的相互作用描述为真正的多体性质,揭示了这种效应如何有效地影响合力的大小甚至方向,特别是那些作用在净电荷为零的粒子上的力。特别注意的情况下,可以与胶体颗粒在电解质溶液中,它的显示,单独的极化效应可以大大提高或降低-取决于粒子和介质之间的介电对比度-能量势垒,划分粒子凝聚和絮凝区域,当静电和额外的范德华力之间的相互作用被认为是。总的来说,结果表明,一个准确的描述类型的系统的问题,它是必不可少的考虑粒子极化,如果相互作用的粒子之间的分离是可比的或小于介质的德拜长度。
Two main approaches in particle-based simulations for modeling a charged surface are using explicit, discrete charges and continuum, uniform charges. It is well-known that these two approaches could lead to substantially distinct ionic distributions, whereas a systematic exploration of the origin is still absent. In this short communication, we calculate the electrostatic force of a single point charge above a planar substrate characterized by a surface charge density and dielectric mismatch and compare the differences in the electrostatic forces produced by discrete and continuum representati…
Electrostatic correlations in inhomogeneous charged fluids beyond loop expansion
本文用静电自洽理论研究了非均匀对称电解质中的静电关联效应。Netz和H.奥兰J. E 11,301(2003))。为了这个目的,我们介绍了两种计算方法,允许解决SC方程以外的循环扩展。这两种方法都可以处理的情况下,介电不连续的边界的单回路理论是已知的失败。通过将从这些方案获得的理论结果与我们在中性单电介质界面处运行的离子的MC模拟结果以及先前的带电界面的MC数据进行比较,我们首先表明弱耦合(WC)Debye-Huckel(DH)理论在体离子密度rhob=0.01 M之前仍然定量准确,而SC理论在rhob= 0.2M时表现出良好的定量精度。然后,我们从微扰SC格式导出了介电均匀带电表面周围非对称分区盐体系的单圈理论。结果表明,相关效应起源于这些系统从盐屏蔽损失之间的竞争,在界面上驱动的离子的散装区域,和界面的countershielding过剩吸引他们向表面。在弱表面电荷的情况下,界面盐屏蔽损失是主要的影响。因此,相关性降低了共离子和反离子的MF密度。随着表面电荷的增加,表面吸引的反离子屏蔽过剩开始占主导地位,相关效应放大这两种类型的离子的MF密度。我们还表明,在一个特征值的静电耦合参数,静电相关的结果在电荷反转效应。
In this paper, we formulate a field-theoretical model of dilute salt solutions of electrically neutral spherical colloid particles. Each colloid particle consists of a 'central' charge that is situated at the center and compensating peripheral charges (grafted to it) that are fixed or fluctuating relative to the central charge. In the framework of the random phase approximation, we obtain a general expression for electrostatic free energy of solution and analyze it for different limiting cases. In the limit of infinite number of peripheral charges, when they can be modelled as a continual char…
Ion size effects at ionic exclusion from dielectric interfaces and slit nanopores
先前开发的场论模型[R. D. Coalson等人,J.Chem.Phys.102,4584(1995)],其在相同的基础上处理核碰撞和库仑相互作用,以理解离子尺寸对中性和带电粒子在平面界面处的分配的影响以及狭缝纳米孔的离子选择性。我们引入了一个变分方案,可以超越平均场(MF)制度,并以一致的方式耦合孔改性的核心相互作用,空间位阻效应,静电溶剂化和图像电荷力,和表面电荷诱导的静电势。我们表明,在稀释的限制,MF和变分理论符合MC模拟结果,在最近的RPA方法相比。研究了带电汤川粒子在中性介质界面(如空气-水或蛋白质-水界面)的分配。它示出,作为一个结果的核心碰撞之间的竞争,推动离子的表面,排斥溶剂化和图像的力量,排除他们从接口,浓度峰值的有限大小的离子集在接近的电介质界面。我们还表征了中性狭缝纳米孔的离子选择性的离子尺寸所发挥的作用。我们发现,复杂的相互作用之间的静电力,排除体积效应引起的核心碰撞和空间效应导致一个意想不到的逆转,在不同孔径的孔的离子选择性:而大孔表现出更高的电导率为大离子,窄孔排除大离子比小的更有效。
Can we avoid molecular dynamics simulations to estimate the electrostatic interaction between charged objects separated by a nanometric distance in water? To answer this question, we develop a continuous model for the dielectric properties of water based on a functional of the polarization. A phenomenological Landau-Ginzburg Hamiltonian for the electrostatic energy of water is parameterized to capture the dipolar correlations in the fluid at the nanometric scale. We show that in this framework, the effective interactions of simple objects such as point charges are analytically tractable. In pa…
We theoretically investigate electrostatic properties between two charged surfaces with a grafted polyelectrolyte layer in an aqueous electrolyte solution by using the Poisson-Boltzmann approach accounting for ion partitioning. In order to consider the ion partitioning effect, we focus on changes of electrostatic properties due to the difference in dielectric permittivity of the polyelectrolyte layer and the aqueous electrolyte solution. We find that ion partitioning enhances electrostatic potential in the region between two charged soft surfaces and hence increases the electrostatic interacti…