title: Exact dynamics of a reaction-diffusion model with spatially alternating rates.
abstract: We present the exact solution for the full dynamics of a nonequilibrium spin chain and its dual reaction-diffusion model, for arbitrary initial conditions. The spin chain is driven out of equilibrium by coupling alternating spins to two thermal baths at different temperatures. In the reaction-diffusion model, this translates into spatially alternating rates for particle creation and annihilation, and even negative "temperatures" have a perfectly natural interpretation. Observables of interest include the magnetization, the particle density, and all correlation functions for both models. Two generic types of time dependence are found: if both temperatures are positive, the magnetization, density, and correlation functions decay exponentially to their steady-state values. In contrast, if one of the temperatures is negative, damped oscillations are observed in all quantities. They can be traced to a subtle competition of pair creation and annihilation on the two sublattices. We comment on the limitations of mean-field theory and propose an experimental realization of our model in certain conjugated polymers and linear chain compounds.
authors.affiliation: Center for Stochastic Processes in Science and Engineering, Department of Physics, Virginia Tech, Blacksburg, Virginia 24061-0435, USA. mmobilia@vt.edu
authors.forename: M
authors.initials: M
authors.lastname: Mobilia
authors.forename: B
authors.initials: B
authors.lastname: Schmittmann
authors.forename: R K P
authors.initials: RK
authors.lastname: Zia