A transferable classical force field to describe glyme based lithium solvate ionic liquids

Area of Science:

• Computational Chemistry
• Materials Science
• Electrochemistry

Background:

• Accurate molecular simulations require reliable force fields to describe ion-solvation interactions.
• Existing force fields may not fully capture the complex behavior of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in glyme solvents.
• Developing transferable force fields is crucial for predicting properties of electrolyte systems.

Purpose of the Study:

• To develop a non-polarizable force field for LiTFSI in diglyme.
• To validate the force field's accuracy against ab initio molecular dynamics (AIMD) simulations and experimental data.
• To assess the force field's transferability to different glyme chain lengths and salt concentrations.

Main Methods:

• Development of a non-polarizable force field using AIMD simulations and a modified polymer consistent force field model.
• Determination of Lennard-Jones parameters via a force-torque matching scheme and genetic algorithm.
• Molecular dynamics (MD) simulations to test the force field's performance and transferability.

Main Results:

• The developed force field accurately reproduces radial distribution functions and experimental x-ray structure factors.
• It demonstrates good agreement with AIMD simulations and experimental data for various salt concentrations and glyme lengths.
• The force field shows transferability to longer glymes (triglyme, tetraglyme) and higher salt concentrations.

Conclusions:

• The new non-polarizable force field accurately describes LiTFSI-glyme systems at the atomistic level.
• It provides a reliable tool for in silico studies of these electrolytes.
• The validated force field enables accurate predictions for systems with varying salt concentrations and solvent chain lengths.