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Pair-correlation functions and phase separation in a two-component point Yukawa fluid

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posted on 2014-10-09, 13:33 authored by Paul Hopkins, Andrew ArcherAndrew Archer, Robert Evans
We investigate the structure of a binary mixture of particles interacting via purely repulsive point Yukawa pair potentials with a common inverse screening length λ. Using the hypernetted chain closure to the Ornstein-Zernike equations, we find that for a system with "ideal" (Berthelot mixing rule) pair-potential parameters for the interaction between unlike species, the asymptotic decay of the total correlation functions crosses over from monotonic to damped oscillatory on increasing the fluid total density at fixed composition. This gives rise to a Kirkwood line in the phase diagram. We also consider a "nonideal" system, in which the Berthelot mixing rule is multiplied by a factor (1+δ). For any δ0 the system exhibits fluid-fluid phase separation and remarkably the ultimate decay of the correlation functions is now monotonic for all (mixture) state points. Only in the limit of vanishing concentration of either species does one find oscillatory decay extending to r=∞. In the nonideal case the simple random-phase approximation provides a good description of the phase separation and the accompanying Lifshitz line. © 2006 American Institute of Physics.


One of the authors (P.H.) is grateful for the support of an EPSRC studentship and another author (A.J.A.) acknowledges the support of EPSRC under Grant No. GR/S28631/01.



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Journal of Chemical Physics






HOPKINS, P., ARCHER, A.J. and EVANS, R., 2006. Pair-correlation functions and phase separation in a two-component point Yukawa fluid. Journal of Chemical Physics, 124 (5), 054503.


© American Institute of Physics


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This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

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Copyright 2006 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Journal of Chemical Physics, 2006, 124 (5), 054503 and may be found at: http://dx.doi.org/10.1063/1.2162884




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