Systematic comparison of force fields for molecular dynamic simulation of Au(111)/Ionic liquid interfaces

Selecting the most suitable force field is a key to meaningful molecular dynamics (MD) simulation. To select the appropriate gold force field to model the Au(111)/ionic liquid interface, a systematic comparison of four different widely used force fields of gold and a typical carbon force field has been studied by MD simulations with constant potential method. We calculated the ion adsorption behavior and differential capacitance of interfaces between the gold electrode and ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([PYR][TFSI]) in comparison with the experimental results and showed the effects on the solid-liquid interfaces from the van der Waals interaction, image force effect and cumulative ions. Based on the comparison between the results of simulations and experiments, we recommend two types of force fields to properly model the Au(111)/ionic liquid interfaces.