Evolution of the universality class in slightly diluted (1 > p > 0.8) Ising systems

The crossover of a pure (undiluted) Ising system (spin per site probability p=1) to a diluted Ising system (spin per site probability p < 0.8) is stud ied by means of Monte Carlo calculations with p ranging between 1 and 0.8 a t intervals of 0.025. The evolution of the self-averaging is analyzed by di rect determination of the normalized square widths R-M and R-x as a functio n of p. We find a monotonous and smooth evolution from the pure to the rand omly diluted universality class. The p-dependent transition is found to be indepent of size (L). This property is very convenient for extrapolation to wards the randomly diluted universality class avoiding complications result ing from finite size effects. (C) 2000 Elsevier Science B.V. All rights res erved.