Period doubling and other complex bifurcations in non-isothermal chemical systems

Abstract

Chemical feedback in the form of chain-branching or autocatalysis can give rise to oscillatory behaviour in very simple models involving only two variables. Many chemical reactions are also exothermic. This chemical heat release can give rise to self-heating and hence to thermal feedback, where the temperature varies as well as the concentrations. When chemical and thermal feedback are coupled, the range of responses that can be observed are increased dramatically. These features are demonstrated through the simple non-isothermal autocatalator scheme p-> A rate = A + 2B-> 3B rate = k1 2, A-^ B rate = kza, C + heat rate = At its simplest, the reaction can be steady or can show simple period-1 oscillations. More complex oscillations, with higher periodicity appear as the experimental conditions are varied, with period doubling, mixed-mode oscillations and aperiodicity (chemical chaos).