Microcanonical simulation of disordered systems

We present the results of microcanonical simulations of the three-dimensional site-diluted antiferromagnetic Ising model, on body-centered cubic lattices of sizes 2 x 40 x 40 x 40 and magnetic concentrations p greater than or equal to 0.325. The temperature and concentration dependence of the magnetization, internal energy, and susceptibility are directly calculated from the simulations, whereas the specific heat is obtained from the numerical derivative of the energy. Our results for the critical energy and critical temperature as functions of the concentration are compared with the experimental results on the diluted antiferromagnet CopZn1-pCs3Cl5. (C) 2001 Elsevier Science B.V. All rights reserved.