Most conventional force fields for ionic liquids to date approximate the intermolecular electrostatic interaction by using fixed point charges. This approximation results in the neglect of important effects including charge density anisotropy and charge density overlap, and consequently results in inaccuracies for some properties with respect to experimental data. One way to address these issues is by improving the description of the electrostatic interactions by employing higher order multipoles. AMOEBA is a multipolar, polarizable force field initially developed to simulate biomolecules. We have recently extended the AMOEBA force field for ionic liquid simulations. In addition, we have shown that new distributed multipoles extracted from Hermite Gaussian functions using the Gaussian electrostatic model (GEM) can be used in AMOEBA. To validate the performance of our new distributed multipoles, called GEM-DM, the parametrization of several imidazolium- and pyrrolidinium-based ionic liquids have been performed. Our results show very good agreement with respect to experiment for several properties. In this contribution, we will discuss the parameter fitting methodology, and present results for properties calculated for several ionic liquid pairs based on our AMOEBA parametrization.

Development of an accurate multipolar-polarizable force field for ionic liquids

249th National Meeting (2015)

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