A molecular dynamics computer simulation study of room-temperature ionic liquids. II. Equilibrium and nonequilibrium solvation dynamics.

摘要: The molecular dynamics (MD) simulation study of solvation structure and free energetics in 1-ethyl-3-methylimidazolium chloride hexafluorophosphate using a probe solute the preceding article [Y. Shim, M. Y. Choi H. J. Kim, Chem. Phys. 122, 044510 (2005)] is extended to investigate dynamic properties these liquids. Solvent fluctuation near equilibrium are studied via MD associated time-dependent friction analyzed generalized Langevin equation. Nonequilibrium solvent relaxation following an instantaneous change charge distribution accompanying reorganization also investigated. Both nonequilibrium characterized by at least two vastly different time scales--a subpicosecond inertial regime followed slow diffusive regime. regions contributing found vary significantly with initial configurations, especially solute. If density sufficiently high outset relaxation, mainly governed motions few ions close By contrast, case low local density, located not only but relatively far from participate relaxation. Despite this difference, linear response holds reasonably well both ionic