Title: MONTE CARLO SIMULATION OF PHASE EQUILIBRIA IN ISING FLUIDS AND THEIR MIXTURES
Author(s): W.Fenz, R.Folk (Institute for Theoretical Physics, Johannes-Kepler-University Linz, Altenbergerstr. 69, A-4040 Linz, Austria)

The mean field theory for the pure Ising fluid was recently extended to binary mixtures of an Ising and a van der Waals fluid. Depending on the relative interaction strengths, their three dimensional phase diagrams show lines of tricritical consolute and plait points, lines of critical end points and magnetic consolute point lines. Our current efforts are to compare these mean field results with different Monte Carlo simulation techniques, investigating both first order (liquid-vapor and demixing) and second order (paramagnetic-ferromagnetic) phase transitions. We show the resulting $\rho,T$ phase diagrams of the pure Ising fluid for different magnetic interaction strengths $R$ and constant pressure cross-sections of the $x,T,p$ phase diagrams of Ising mixtures for different relative interaction strengths. The methods we have used include Gibbs Ensemble MC, Multihistogram Reweighting, Hyper-parallel Tempering, the cumulant intersection method and the newly developed Density of States MC technique.

Key words: magnetic fluid, binary mixture, Monte Carlo simulation, phase diagram, tricritical point
PACS: 05.70.Fh, 82.60.Lf, 64.60.-i, 64.60.Kw, 02.70.Uu