title: Calculation of the intrinsic solvation free energy profile of an ionic penetrant across a liquid-liquid interface with computer simulations.
abstract: We introduce the novel concept of an intrinsic free energy profile, allowing one to remove the artificial smearing caused by thermal capillary waves, which renders difficulties for the calculation of free energy profiles across fluid interfaces in computer simulations. We apply this concept to the problem of a chloride ion crossing the interface between water and 1,2-dichloroethane and show that the present approach is able to reveal several important features of the free energy profile which are not detected with the usual, nonintrinsic calculations. Thus, in contrast to the nonintrinsic profile, a free energy barrier is found at the aqueous side of the (intrinsic) interface, which is attributed to the formation of a water "finger" the ion pulls with itself upon approaching the organic phase. Further, by the presence of a nonsampled region, the intrinsic free energy profile clearly indicates the coextraction of the first hydration shell water molecules of the ion when entering the organic phase.
authors.affiliation: Sector of Molecular and Statistical Biophysics, SISSA , 265 via Bonomea, I-34136 Trieste, Italy.
authors.forename: Mária
authors.initials: M
authors.lastname: Darvas
authors.forename: Miguel
authors.initials: M
authors.lastname: Jorge
authors.forename: M Natalia D S
authors.initials: MN
authors.lastname: Cordeiro
authors.forename: Sofia S
authors.initials: SS
authors.lastname: Kantorovich
authors.forename: Marcello
authors.initials: M
authors.lastname: Sega
authors.forename: Pál
authors.initials: P
authors.lastname: Jedlovszky
mesh_terms: D003198:Computer Simulation; D017136:Ion Transport; D056004:Molecular Dynamics Simulation; D012997:Solvents / Q000737:chemistry*
chemical_list: D012997:Solvents