Münster 1999 – wissenschaftliches Programm
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DY: Dynamik und Statistische Physik
DY 52: Phasenumwandlungen und kritische Phänomene
DY 52.5: Vortrag
Freitag, 26. März 1999, 12:15–12:30, R4
Damage spreading and the existence of many pure states in the random field Ising model — •Thomas Vojta1, Predrag Lazić1,2, Michael Schreiber1, and Eric Straver1,3 — 1Institut für Physik, Technische Universität Chemnitz — 2Department of Physics, University of Zagreb, Kroatia — 3Department of Applied Physics, Stanford University, USA
We numerically investigate the spreading of damage in the random field Ising model. In this type of simulations two replicas of the system with slightly different initial conditions are subjected to the same thermal noise. The damage, i.e. the difference between the two replicas will either spread or heal, depending on the parameters of the model. We particularly study how the random field influences the stationary damage values and the spreading transition temperature. We find that the results for very weak and for very strong random fields are in agreement with a recent mean-field theory [T. Vojta, J. Phys. A 30, L643 (1997)]. In contrast, at intermediate random field strength the stationary damage varies from sample to sample and also strongly depends on the initial conditions. This reflects the existence of many pure states in the random-field Ising model. We discuss, how damage spreading can be used to determine details of the complicated free energy landscape.