Freezing and correlations in fluids with competing interactions

We consider fluids in which the attractive interaction at distances slightly larger than the particle size is dominated at larger distances by a repulsive contribution. A previous investigation of the effects of the competition between attraction and repulsion on the liquid-vapour transition and on...

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Bibliographic Details
Published in:Journal of physics. Condensed matter 2006-09, Vol.18 (36), p.S2305-S2320
Main Authors: Pini, D, Parola, A, Reatto, L
Format: Article
Language:English
Subjects:
Condensed matter: structure, mechanical and thermal properties
Equations of state, phase equilibria, and phase transitions
Equilibrium properties near critical points, critical exponents
Exact sciences and technology
General studies of phase transitions
Liquid-vapor transitions
Physics
Specific phase transitions
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Summary:We consider fluids in which the attractive interaction at distances slightly larger than the particle size is dominated at larger distances by a repulsive contribution. A previous investigation of the effects of the competition between attraction and repulsion on the liquid-vapour transition and on the correlations is extended to the study of the stability of liquid-vapour phase separation with respect to freezing. We find that this long-range repulsive part of the interaction expands the region in which the fluid-solid transition preempts the liquid-vapour one, so the critical point becomes metastable at longer attraction ranges than those required for purely attractive potentials. Moreover, the large density fluctuations that occur near the liquid-vapour critical point are greatly enhanced by the competition between attractive and repulsive forces, and encompass a much wider region than in the attractive case. The decay of correlations for states in which the compressibility is large is governed by two characteristic lengths, and the usual Ornstein-Zernike picture breaks down except for the very neighbourhood of the critical point, where one length reduces to the commonly adopted correlation length, while the other one saturates at a finite value.
ISSN:0953-8984
1361-648X
DOI:10.1088/0953-8984/18/36/S06