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arXiv · 1804.07408

Size and shape dependence of finite volume Kirkwood-Buff integrals

Peter Krüger·Thijs J. H. Vlugt
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Abstract

Analytic relations are derived for finite volume integrals over the radial distribution function of a fluid, so-called Kirkwood-Buff integrals. Closed form expressions are obtained for cubes and cuboids, the system shapes commonly employed in molecular simulations. When finite volume Kirkwood-Buff integrals are expanded over inverse system size, the leading term depends on shape only through the surface area to volume ratio. This conjecture is proved for arbitrary shapes and a general expression for the leading term is derived. From this, a new extrapolation to the infinite volume limit is proposed, which converges much faster with system size than previous approximations and thus significantly simplifies the numerical computations.

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Peter Krüger, Thijs J. H. Vlugt. 2018-05-05. Size and shape dependence of finite volume Kirkwood-Buff integrals. https://doi.org/10.1103/physreve.97.051301

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