STOCHASTIC ASPECTS OF NONEQUILIBRIUM PHASE-TRANSITIONS

Nonlinear model systems based on Eigen's theory of macromolecular self-organization are investigated stochastically. Nonequilibrium phases are usually achieved through delicate transient processes from an initial condition. The minimum initial values required for a secure relaxation to the expected phase are estimated for the case of internal fluctuation and for the system perturbed by multiplicative white noises. These values set the criterion for the stochastic transition from the survival phase to extinction phase. It is found that, over a narrow critical region preceding the noise-induced transition point, the relaxation time diverges abruptly while the effective domain for a secure relaxation shrinks drastically. Numerical results also demonstrate that Stratonovich calculi are favored over Ito calculi in describing the dynamic systems. © 1990 The American Physical Society.