Microcanonical simulation of disordered systems

We present the results of microcanonical simulations of the three-dimension al site-diluted antiferromagnetic Ising model, on body-centered cubic latti ces 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 magnet ization, internal energy, and susceptibility are directly calculated from t he simulations, whereas the specific heat is obtained from the numerical de rivative of the energy. Our results for the critical energy and critical te mperature as functions of the concentration are compared with the experimen tal results on the diluted antiferromagnet CopZn1-pCs3Cl5. (C) 2001 Elsevie r Science B.V. All rights reserved.