Computer simulations of single particles in external electric fields

TL;DR

This paper reviews recent coarse-grained simulations that explore how single particles and macromolecules in electrolyte solutions respond dynamically and dielectrically to external electric fields, revealing complex electrostatic and hydrodynamic interactions.

Contribution

It provides a comprehensive overview of simulation methods and recent advances in understanding particle responses to electric fields at the molecular level.

Findings

Charged particles exhibit electrophoretic mobility in DC fields.

Uncharged and charged particles show complex polarizability in AC fields.

Recent simulation algorithms improve understanding of electrohydrodynamic interactions.

Abstract

Applying electric fields is an attractive way to control and manipulate single particles or molecules, e.g., in lab-on-a-chip devices. However, the response of nanosize objects in electrolyte solution to external fields is far from trivial. It is the result of a variety of dynamical processes taking place in the ion cloud surrounding charged particles and in the bulk electrolyte, and it is governed by an intricate interplay of electrostatic and hydrodynamic interactions. Already systems composed of one single particle in electrolyte solution exhibit a complex dynamical behaviour. In this review, we discuss recent coarse-grained simulations that have been performed to obtain a molecular-level understanding of the dynamic and dielectric response of single particles and single macromolecules to external electric fields. We address both the response of charged particles to constant fields (DC fields), which can be characterized by an electrophoretic mobility, and the dielectric response of both uncharged and charged particles to alternating fields (AC fields), which is described by a complex polarizability. Furthermore, we give a brief survey of simulation algorithms and highlight some recent developments.