DAMAGE SPREADING IN THE ISING-MODEL WITH A MICROCANONICAL CONSTRAINT

We study damage spreading in the ferromagnetic Ising model, on the squ are lattice, by performing numerical simulations in the microcanonical ensemble. Although the damage spreads for all temperature values, a d ynamical critical phenomenon is observed at T-d = 1.020(2)T-C (T-C is the Curie temperature): For T greater than or equal to T-d the damage D(t) is insensitive to its initial value D(0), while for T < T-d a wea k dependence on D(0) is present in such a way that for each T there ar e two values of D(t) corresponding to the initial conditions D(0) < 1/ 2 and D(0) > 1/2. We have also identified a convenient order parameter to characterize the transition occurring at T-d.