Including many-body effects in models for ionic liquids

TL;DR

This paper develops two advanced molecular dynamics models for ionic liquids that explicitly incorporate many-body effects, including dipole and quadrupole polarization, using parameters derived from first-principles calculations.

Contribution

It introduces two novel models that explicitly include many-body effects in ionic liquids, with parameters obtained from density functional theory, enhancing the realism of simulations.

Findings

Models successfully incorporate many-body effects.

Parameters derived from first-principles improve accuracy.

Potential for better predictive simulations of ionic systems.

Abstract

Realistic modeling of ionic systems necessitates taking explicitly account of many-body effects. In molecular dynamics simulations, it is possible to introduce explicitly these effects through the use of additional degrees of freedom. Here we present two models: The first one only includes dipole polarization effect, while the second also accounts for quadrupole polarization as well as the effects of compression and deformation of an ion by its immediate coordination environment. All the parameters involved in these models are extracted from first-principles density functional theory calculations. This step is routinely done through an extended force-matching procedure, which has proven to be very succesfull for molten oxides and molten fluorides. Recent developments based on the use of localized orbitals can be used to complement the force-matching procedure by allowing for the direct calculations of several parameters such as the individual polarizabilities.