Generation of multiple attractors and nonequilibrium phase transitions

We develop and discuss the generation of new limit cycles in chemical systems by external periodic perturbations. The deterministic analysis is based on prior work by Loud. We choose a model derived from experiments, the conversion of 2,3 epoxy-1-propanol to glycerine. The autonomous system of equations which govern the dynamics of this system has a limit cycle arising from a normal Hopf bifurcation, and a stable focus, and a limit cycle associated with an inverted Hopf bifuraction. For specific choices of periodic perturbations a prescribed number of periodic attractors can be generated from a single periodic attractor (normal Hopf bifurcation); and two periodic attractors, a periodic and biperiodic, or two biperiodic attractors can be generated from a stable focus and periodic attractor (inverted Hopf bifurcation). Noise is then imposed on the attractors of the autonomous system and the multiple attractors of the externally forced system. Noise imposed on the autonomous system with a stable focus and limit cycle causes random transitions, analogous to first order phase transitions. This behavior has some resemblance to intermittency noted in some biological systems. From the results of noise imposed on systems with different numbers of isoperiodic limit cycles we suggest, after a limited number of observations, the trend that as the number of attractors increases, the lines in the power spectrum narrow and the area in the phase plane within contours of equal probability increases.