Phase transformations in the disordered antiferromagnetic Ising model

We employ the Monte Carlo method to provide a computer description of the thermodynamic properties of the disordered antiferromagnetic Ising model for a simple cubic lattice with allowance for the nearest neighbors interaction and the next-nearest neighbors interaction. We construct the phase diagram for the model in an external magnetic field for systems with spin concentrations p=1.0, 0.95, and 0.8. We also establish the tricritical behavior of the model. Finally, we study the critical behavior of the model in weak fields.