Abstract
The Kirkwood–Buff (KB) theory provides an important connection between microscopic density fluctuations in liquids and macroscopic properties. Recently, Krüger et al. derived equations for KB integrals for finite subvolumes embedded in a reservoir. Using molecular simulation of finite systems, KB integrals can be computed either from density fluctuations inside such subvolumes, or from integrals of radial distribution functions (RDFs). Here, based on the second approach, we establish a framework to compute KB integrals for subvolumes with arbitrary convex shapes. This requires a geometric function w(x) which depends on the shape of the subvolume, and the relative position inside the subvolume. We present a numerical method to compute w(x) based on Umbrella Sampling Monte Carlo (MC). We compute KB integrals of a liquid with a model RDF for subvolumes with different shapes. KB integrals approach the thermodynamic limit in the same way: for sufficiently large volumes, KB integrals are a linear function of area over volume, which is independent of the shape of the subvolume.
Original language  English 

Pages (fromto)  15731580 
Journal  Molecular Physics: an international journal at the interface between chemistry and physics 
Volume  116 
Issue number  12 
DOIs  
Publication status  Published  2018 
Keywords
 Kirkwood–Buff integrals
 smallsystems thermodynamics
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Kirkwood–Buff integrals of finite systems: geometric functions w(x)
Vlugt, T. J. H. (Creator), Dawass, N. (Creator), Krüger, P. (Contributor) & Simon, J. M. (Contributor), TU Delft  4TU.ResearchData, 8 Mar 2018
DOI: 10.4121/UUID:9C897EF29DE0433ABDC4ECABBC340D5B
Dataset/Software: Dataset