Monte Carlo Studies of the Ising Antiferromagnet with a Ferromagnetic Mean-field Term

The unusual thermodynamic properties of the Ising antiferromagnet supplemented with a ferromagnetic, mean- field term are outlined. This simple model is inspired by more realistic models of spin-crossover materials. The phase diagram is estimated using Metropolis Monte Carlo methods, and differences with preliminary Wang-Landau Monte Carlo results for small systems are noted.