2002/11/30 by T. Hanney, M. R. Evans
Physics and Astronomy · #cond-mat.stat-mech
published as J. Stat. Phys. 111, 1377-1390 (2003) · 14 pages; minor clarifications, reference added
arxiv created 2003/03/03 · arxiv updated 2009/11/30
The Einstein relation, relating the steady state fluctuation properties to the linear response to a perturbation, is considered for steady states of stochastic models with a finite state space. We show how an Einstein relation always holds if the steady state satisfies detailed balance. More generally, we consider nonequilibrium steady states where detailed balance does not hold and show how a generalisation of the Einstein relation may be derived in certain cases. In particular, for the asymmetric simple exclusion process and a driven diffusive dimer model, the external perturbation creates and annihilates particles thus breaking the particle conservation of the unperturbed model.