We study the nonequilibrium phase transition in the one-dimensional contact process with quenched spatial disorder by means of large-scale Monte Carlo simulations for times up to 109 and system sizes up to 107 sites. In agreement with recent predictions of an infinite-randomness fixed point, our simulations demonstrate activated (exponential) dynamical scaling at the critical point. The critical behavior turns out to be universal, even for weak disorder. However, the approach to this asymptotic behavior is extremely slow, with crossover times of the order of 104 or larger. In the Griffiths region between the clean and the dirty critical points, we find power-law dynamical behavior with continuously varying exponents. We discuss the generality of our findings and relate them to a broader theory of rare region effects at phase transitions with quenched disorder.
T. Vojta and M. Dickison, "Critical Behavior and Griffiths Effects in the Disordered Contact Process," Physical Review E: Statistical, Nonlinear, and Soft Matter Physics, American Physical Society (APS), Jan 2005.
The definitive version is available at http://dx.doi.org/10.1103/PhysRevE.72.036126
National Science Foundation (U.S.)
University of Missouri Research Board
Library of Congress Subject Headings
Monte Carlo method
Phase transformations (Statistical physics)
Article - Journal
© 2005 American Physical Society (APS), All rights reserved.