A Molecular Dynamics Study on the Magnetic Imidazolium-based Ionic Liquids: Effect of an External Magnetic Field
This paper serves as a molecular dynamics (MD) study on the properties of three different magnetic imidazolium-based ionic liquids in the absence and presence of external magnetic field. In this regard, the volumetric properties such as density and isobaric expansion coefficient, dynamical properties, namely, viscosity, mean square displacement of ions, diffusion coefficients, transport numbers of cation and anion, and electrical conductivity, structural properties such as radial distribution function (RDF) and spatial distribution function (SDF) of [emim][FeCl4], [bmim][FeCl4] and [hmim][FeCl4] are studied at different temperatures using molecular dynamics simulation method. After studying the different volumetric, structural, and dynamical properties of the mentioned magnetic ILs in the absence of magnetic field, we investigated the effect of external magnetic field on the structural properties of one of these systems, i.e. [bmim][FeCl4]. In this regard, we established different contributions in the interactions between external magnetic field and the studied magnetic ionic liquid (MIL). Number density profiles of the studied MIL before and after imposing external magnetic field of 1.5 T show a significant variation in the molecular distribution. The results show that the external magnetic field reduce the intensity of the RDFs due to the reduction in the interactions between different sites of ions as a result of changing in their orientations. By applying the external magnetic field, due to oppositely directed forces on the cations and anions, they move in opposite directions. The snapshots show that the static distortion of the anion is smaller because of its small size. In the presence of external magnetic field, the ions distribute more homogenously compared to the absence of this field. Results of this study can be used in the clever and accurate design of viscomagnetic fluids and reaction systems in the presence and absence of magnetic fields.