Development of AMOEBA Force Field for 1,3-Dimethylimidazolium Based Ionic Liquids

Abstract

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 [NO(3)(-)], and tetraflorouborate [BF(4)(-)], 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 ρ, enthalpies of vaporization ΔH(vap), and diffusion coefficients D(±) in comparison with conventional force fields.

Current Status of AMOEBA–IL: A Multipolar/Polarizable Force Field for Ionic Liquids

“…In all cases, the bonded terms have been taken from the original AMOEBA parameters where available. For the bonded AMOEBA parameters that have not been previously reported, torsional scans have been obtained at the MP2/6-311G(d,p) level [102].…”

“…All parameters for the non-bonded terms for AMOEBA-IL are fitted using counterpoise corrected QM inter-molecular interaction energies and QM energy decomposition analysis (EDA) for representative dimers [102][103][104][105][106]. The QM EDA data is employed to fit and compare the individual Coulomb, polarization and Van der Waals AMOEBA terms to reduce the error of each term.…”

“…The QM EDA data is employed to fit and compare the individual Coulomb, polarization and Van der Waals AMOEBA terms to reduce the error of each term. The original parametrization for the dimethyl imidazolium-based systems employed the restricted variational space (RVS) approach for the QM EDA reference using dimers in a single orientation at different distances [102,103].…”

General van der Waals potential for common organic molecules

“…During the past decade, the AMOEBA polarizable force field 14 has been extensively tested for water, 15 various small molecules, 16 ions, 17 ionic liquids, 18 and proteins systems. 19 However, due to the missing treatment of charge penetration, atomic multipoles are unable to capture electrostatic interactions at very short range where the atomic electron clouds overlap.…”

Computational Investigation of O2Diffusion Through an Intra–molecular Tunnel in AlkB; Influence of Polarization on O2Transport

“…65,66 AMOEBA combines distributed atomic multipoles (up to quadrupole) and (Tholé damped) inducible atomic dipoles, which have been shown to provide an accurate representation for various systems. 37,53,57,58,[67][68][69][70][71][72] Umbrella sampling/WHAM calculations for the AMOEBA calculations were performed using the amoebabio09 potential 73 using the same windows as for the ff99SB calculations. A harmonic potential (10 kcal mol −1 Å −2 , same as for the ff99SB PMF) was for each window.…”