Molecular dynamics studies of melting and some liquid-state properties of 1-ethyl-3-methylimidazolium hexafluorophosphate [emim][PF6] -: art. no. 154704

Molecular dynamics simulations are used to study the liquid-state properties and melting of 1-ethyl-3-methylimidazolium hexafluorosphosphate, [emim][PF6] using the force field of Canongia Lopes et al. [J. Phys. Chem. B 108, 2038 (2004)] and geometric constants from crystallographic data. The structures of the solid and liquid states are characterized by carbon-carbon, carbon-phosphorous, and phosphorous-phosphorous radial distribution functions. Spatial correlations among the ions are. strong in the liquid state. The cohesive energy density and the temperature dependences of the molar volume and density of the liquid have been computed. The melting point is determined by equilibrating the solid-state supercells in which void defects have been introduced to eliminate the free-energy barrier for the formation of a solid-liquid interface. The computed melting point is 375 +/- 10 K, which is approximately 10% higher than the experimental value of 333 K. (c) 2005 American Institute of Physics.