title: Scaling Atomic Partial Charges of Carbonate Solvents for Lithium Ion Solvation and Diffusion.
abstract: Lithium-ion solvation and diffusion properties in ethylene carbonate (EC) and propylene carbonate (PC) were studied by molecular simulation, experiments, and electronic structure calculations. Studies carried out in water provide a reference for interpretation. Classical molecular dynamics simulation results are compared to ab initio molecular dynamics to assess nonpolarizable force field parameters for solvation structure of the carbonate solvents. Quasi-chemical theory (QCT) was adapted to take advantage of fourfold occupancy of the near-neighbor solvation structure observed in simulations and used to calculate solvation free energies. The computed free energy for transfer of Li+to PC from water, based on electronic structure calculations with cluster-QCT, agrees with the experimental value. The simulation-based direct-QCT results with scaled partial charges agree with the electronic structure-based QCT values. The computed Li+/PF6-transference numbers of 0.35/0.65 (EC) and 0.31/0.69 (PC) agree well with NMR experimental values of 0.31/0.69 (EC) and 0.34/0.66 (PC) and similar values obtained here with impedance spectroscopy. These combined results demonstrate that solvent partial charges can be scaled in systems dominated by strong electrostatic interactions to achieve trends in ion solvation and transport properties that are comparable to ab initio and experimental results. Thus, the results support the use of scaled partial charges in simple, nonpolarizable force fields in future studies of these electrolyte solutions.
authors: Center for Biological and Engineering Sciences, Sandia National Laboratories , Albuquerque, New Mexico 87185, United States.
authors: Mangesh I
authors: MI
authors: Chaudhari
authors: Department of Applied Science and Technology, Politecnico di Torino , Turin 10129, Italy.
authors: Jijeesh R
authors: JR
authors: Nair
authors: Department of Chemical and Biomolecular Engineering, Tulane University , New Orleans, Louisiana 70118, United States.
authors: Lawrence R
authors: LR
authors: Pratt
authors: Department of Chemical Engineering, Texas A&M University , College Station, Texas 77843, United States.
authors: Fernando A
authors: FA
authors: Soto
authors: Department of Chemical Engineering, Texas A&M University , College Station, Texas 77843, United States.
authors: Perla B
authors: PB
authors: Balbuena
authors: Center for Biological and Engineering Sciences, Sandia National Laboratories , Albuquerque, New Mexico 87185, United States.
authors: Susan B
authors: SB
authors: Rempe