Development of AMOEBA Force Field for 1,3-Dimethylimidazolium Based Ionic Liquids
ON Starovoytov and H Torabifard and GA Cisneros, JOURNAL OF PHYSICAL CHEMISTRY B, 118, 7156-7166 (2014).
The development of AMOEBA (a multipolar polarizable force field) for imidazolium based ionic liquids is presented. Our parametrization method follows the AMOEBA procedure and introduces the use of QM intermolecular total interactions as well as QM energy decomposition analysis (EDA) to fit individual interaction energy components. The distributed multipoles for the cation and anions have been derived using both the Gaussian distributed multipole analysis (GDMA) and Gaussian electrostatic model- distributed multipole (GEM-DM) methods.(1) The intermolecular interactions of a 1,3-dimethylimidazolium dmim(+) cation with various anions, including fluoride F-, chloride Cl-, nitrate NO3-, and tetraflorouborate BF4-, were studied using quantum chemistry calculations at the MP2/6-311G(d,p) level of theory. Energy decomposition analysis was performed for each pair using the restricted variational space decomposition approach (RVS) at the HF/6-311G(d,p) level. The new force field was validated by running a series of molecular dynamic (MD) simulations and by analyzing thermodynamic and structural properties of these systems. A number of thermodynamic properties obtained from MD simulations were compared with available experimental data. The ionic liquid structure reproduced using the AMOEBA force field is also compared with the data from neutron diffraction experiment and other MD simulations. Employing GEM-DM force ;fields resulted in a good agreement on liquid densities rho, enthalpies of vaporization Delta H-vap, and diffusion coefficients D-+/- in comparison with conventional force fields.
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