The Phenomenological Account for Electronic Polarization in Ionic Liquid

Abstract

Although a great variety of classical force fields (FFs) for room-temperature ionic liquids (RTILs) have been recently suggested, no systematically derived non-polarizable model is able to reproduce their transport properties, i.e. diffusion constants, conductivities and viscosities. In the present paper, we show that modern FFs greatly overestimate pairwise electrostatic interaction energies in the RTILs systems leading to extremely hindered ionic motions. Based on the results of our ab initio molecular dynamics calculations using explicit ionic environment, we modified the electrostatic interaction potential of 1-ethyl-3-methylimidazolium tetrafluoroborate. Starting from FF, originally derived by Liu et al., we further refined it, so that it reproduces experimental transport properties without compromizing either structure or thermodynamics. The main advantages of the suggested phenomenological account for electronic polarization are its consistency, clearness, simplicity and the possibility to improve functionality of the existing FFs by modifying exclusively atomic partial electrostatic charges.