Phys. Rev. E 71, 061504 (2005) [8 pages]Liquid-liquid phase transition for an attractive isotropic potential with wide repulsive rangeReceived 10 November 2004; revised 8 February 2005; published 17 June 2005 We investigate how the phase diagram of a repulsive soft-core attractive potential, with a liquid-liquid phase transition in addition to the standard gas-liquid phase transition, changes by varying the parameters of the potential. We extend our previous work on short soft-core ranges to the case of large soft-core ranges, by using an integral equation approach in the hypernetted-chain approximation. We show, using a modified van der Waals equation we recently introduced, that if there is a balance between the attractive and repulsive part of the potential this potential has two fluid-fluid critical points well separated in temperature and in density. This implies that for the repulsive (attractive) energy UR(UA) and the repulsive (attractive) range wR(wA) the relation UR∕UA∝wR∕wA holds for short soft-core ranges, while UR∕UA∝3wR∕wA holds for large soft-core ranges. © 2005 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevE.71.061504
DOI:
10.1103/PhysRevE.71.061504
PACS:
61.20.Gy, 61.20.Ne, 61.25.Mv, 64.60.Kw
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