Study on the Characteristics of BMIMPF6 by MD

• 1、School of Mechanical Engeering,Southeast University,Nanjing 211189

Abstract：In order to study the basic properties of room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), a model based on CHARMM force field was constructed and simulated by molecular dynamics method. The results show that under the CHARMM force field, the basic parameters such as molar volume, mass density and bulk expansion rate of BMIMPF6 can better match the experimental data, and the error is low. The calculation of the radial distribution function of anion and cation shows that the nearest distance between the anion and the cation is 3.6 ?, and the formation of the first three solvation shells of the cation-anion pair occurs at about 4.5 ?, 10.7 ? and 17.8 ?, respectively, and the cation-cation The first peak in the radial distribution appears at 7.7 ?, and the cathode-anion radial distribution has two peaks at 6.4 and 9.0 ?; and the inter-coulomb coulomb interaction is strong, and the radial distribution oscillation sequence continues to exceed 20 ?. In addition, the diffusion coefficient and conductivity of BMIMPF6 at room temperature were calculated. The results show that the diffusion coefficients of BMIPF6 anion and cation at room temperature are 7.61μm2/S and 6.01μm2/S, which are much smaller than the general aqueous solution because the viscosity is larger. The conductivity is 0.243 S/m2 at room temperature, which is in agreement with the experimental measurements.

Keywords： Room temperature ionic liquid molecular dynamics simulation molar volume radial distribution function diffusion coefficient