School of Design, Engineering and Computing, Bournemouth University, Poole House, Talbot Campus, Poole, Dorset BH12 5BB, United Kingdom.
School of Physical Sciences, University of Kent, Canterbury, Kent CT2 7NH, United Kingdom.
J Chem Phys. 2014 Jan 14;140(2):024506. doi: 10.1063/1.4858405.
The electrostatic interaction between finite charge distributions, ρ(r), in a neutralizing background is considered as an extension of the one component plasma (OCP) model of point charges. A general form for the interaction potential is obtained which can be applied to molecular theories of many simple charged fluids and mixtures and to the molecular dynamics (MD) simulation of such systems. The formalism is applied to the study of a fluid of Gaussian charges in a neutralizing background by MD simulation and using hypernetted-chain integral equation theory. The treatment of these interactions is extended to a periodic system using a Fourier Transform formulation and, for a rapidly decaying charge distribution, an application of the Ewald method. The contributions of the self-energy and neutralizing background to the system's energy are explicitly included in the formulation. Calculations reveal differences in behavior from the OCP model when the Wigner-Seitz radius is of order and less than the Gaussian charge density decay length. For certain parameter values these systems can exhibit a multiple occupancy crystalline phase at high density which undergoes re-entrant melting at higher density. An exploration of the effects of the various length scales of the system on the equation of state and radial distribution function is made.
在中和背景中，有限电荷分布ρ(r)之间的静电相互作用被视为点电荷单组分等离子体(OCP)模型的扩展。得到了一种可以应用于许多简单带电流体和混合物的分子理论以及这些系统的分子动力学(MD)模拟的通用相互作用势形式。该形式主义被应用于通过 MD 模拟和使用超网链积分方程理论研究中性背景中的高斯电荷流体。通过傅里叶变换公式将这些相互作用扩展到周期性系统中，并在电荷分布迅速衰减的情况下，应用 Ewald 方法。在公式中明确包含了自能和中和背景对系统能量的贡献。计算结果表明，当维格纳-塞茨半径与高斯电荷密度衰减长度相当或小于该长度时，系统的行为与 OCP 模型存在差异。对于某些参数值，这些系统在高密度下可以表现出多占据晶相，在更高密度下经历再进入熔化。对系统的各种长度尺度对状态方程和径向分布函数的影响进行了探讨。
