title: Calculating thermodynamic properties from fluctuations at small scales.
abstract: We show how density and energy fluctuations of small nonperiodic systems embedded in a reservoir can be used to determine macroscopic thermodynamic properties like the enthalpy density and the thermodynamic correction factor. For mixtures, the same formalism leads to a very convenient method to obtain so-called total correlation function integrals, also often referred to as Kirkwood-Buff integrals. Using finite size scaling, the properties obtained for small systems can be extrapolated to the macroscopic system limit provided that the system is sufficiently far from the critical point. As derived in our previous work (Chem. Phys. Lett. 2011, 504, 199-201), the finite size scaling is significant and depends on 1/L, where L is the length of the small system in one dimension. By considering a reservoir with an ensemble of embedded small systems, we can use the scaling arising from surface effects to determine properties for macroscopic systems by extrapolation. We demonstrate this method for the WCA and LJ fluids, as well a for a heterogeneous system, i.e., argon adsorbed in silicalite-1 zeolite.
authors.affiliation: Process and Energy Laboratory, Delft University of Technology, Leeghwaterstraat 44, 2628CA Delft, The Netherlands.
authors.forename: Sondre K
authors.initials: SK
authors.lastname: Schnell
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Simon
authors.forename: André
authors.initials: A
authors.lastname: Bardow
authors.forename: Dick
authors.initials: D
authors.lastname: Bedeaux
authors.forename: Thijs J H
authors.initials: TJ
authors.lastname: Vlugt
authors.forename: Signe
authors.initials: S
authors.lastname: Kjelstrup