FIRST-ORDER NONEQUILIBRIUM PHASE-TRANSITION IN A SPATIALLY EXTENDED SYSTEM

We investigate a system of harmonically coupled identical nonlinear co nstituents subject to noise in different spatial arrangements. For glo bal coupling, we fmd for infinitely many constituents the coexistence of several ergodic components and a bifurcation behavior like in first -order phase transitions. These results are compared with simulations for finite systems both for global coupling and for nearest-neighbor c oupling on two-and three-dimensional cubic lattices. The mean-field-ty pe results for global coupling provide a better understanding of the m ore complex behavior in the latter case.