The general AMBER force field (GAFF) can accurately predict thermodynamic and transport properties of many ionic liquids.
Sprenger KG, Jaeger VW, Pfaendtner J. The general AMBER force field (GAFF) can accurately predict thermodynamic and transport properties of many ionic liquids. J Phys Chem B. 2015 May 07; 119(18):5882-95.