Development of Force Fields and Molecular Dynamics Simulations of Ionic Liquids and Crystals

A many-body polarizable force field has been developed and validated for ionic liquids (ILs) containing 1-methyl-3-alkylimidazolium, 1-alkyl-2-methyl-3-alkylimidazolium, N-methyl-N-alkylpyrrolidinium, N-alkylpyridinium, N-alkyl-N-alkylpiperidinium, N-alkyl-N-alkylmorpholinium, tetraalkylammonium, tetraalkylphosphonium, N-methyl-N-oligoetherpyrrolidinium cations and BF4-, CF3BF3-, CH3BF3-, CF3SO3-, PF6-, dicyanamide, tricyanomethanide, tetracyanoborate, bis(trifluoromethane sulfonyl) imide (Ntf2- or TFSI-), bis(fluorosulfonyl)imide (FSI-) and nitrate anions. Classical molecular dynamics (MD) simulations have been performed on 30 ionic liquids at 298 K, 333 K and 393 K. The IL density, heat of vaporization, ion self-diffusion coefficient, conductivity and viscosity were found in a good agreement with available experimental data. Ability of the developed force field to predict ionic crystal cell parameters has been tested on four ionic crystals containing Ntf2- anions. Developed force field has also provided accurate description/prediction of thermodynamic and transport properties of alkanes, fluoroalkanes, oligoethers (1,2-dimethoxyethane), ethylene carbonate, propylene carbonate, dimethyl carbonate, hydrazine, methyhydrazine, dimethylhydrazine, acetonitrile, dimethyl amine and dimethyl ketone. The relation between ionic liquid transport and thermodynamic properties will be discussed.