A comparative study of two classical force fields on statics and dynamics of [EMIM][BF4] investigated via molecular dynamics simulations

The influences of two different commonly employed force fields on statical and dynamical properties of ionic liquids are investigated for [EMIM][BF4]. The force fields compared in this work are the one of Canongia Lopes and Padua [J. Phys. Chem. B 110, 19586 (2006)] and that of Liu [J. Phys. Chem. B 108, 12978 (2004)]. Differences in the strengths of hydrogen bonds are found, which are also reflected in the static ion distributions around the cation. Moreover, due to the stronger hydrogen bonding in the force field of Liu , the diffusive motions of cations and anions and the rotational behavior of the cations are slower compared with those obtained with the force field of Canongia Lopes and Padua. Both force fields underestimate the zero-field electrical conductivity, while the experimental dielectric constant can be reproduced within the expected statistical error boundaries.