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DY: Dynamik und Statistische Physik

DY 44: Critical Phenomena and Phase Transitions III

DY 44.4: Vortrag

Donnerstag, 30. März 2006, 15:30–15:45, H\"UL 186

Integral equation study of an ideal Ising mixture — •Wolfgang Fenz¹, Igor Omelyan^1,2, and Reinhard Folk¹ — ¹Institute for Theoretical Physics, Linz University, Altenberger Str. 69, A-4040 Linz, Austria — ²Institute for Condensed Matter Physics, 1 Svientsitskii Street, UA-79011 Lviv, Ukraine

We construct an integral equation scheme for magnetic binary mixtures of an ideal soft-core Ising fluid and a soft-sphere fluid by mapping the system onto an equivalent nonmagnetic ternary mixture. We apply the multi-component Ornstein-Zernike equation together with a closure relation based on the soft mean spherical approximation and a field constraint for the Ising fluid component. Phase coexistence curves at constant pressure or temperature are calculated both by directly evaluating the chemical potentials via the bridge function [1], and by using a Maxwell-like construction. Our results are compared to Monte Carlo data obtained earlier [2], and we find that the second method yields much better agreement with the simulations.

Supported by the Austrian Fonds zur Förderung der wissenschaftlichen Forschung, project No P18592.

[1] L. L. Lee, J. Chem. Phys. 97, 8606 (1992)

[2] W. Fenz and R. Folk, Phys. Rev. E 71, 046104 (2005)

[3] W. Fenz, I. Omelyan, and R. Folk, to be published in Phys. Rev. E