Enhanced sensitivity of a thermochemical system to microscopic perturbations

We study a thermochemical system at different description levels. The results of the mesosocopic description based on the master equation and microscopic simulations of the particle dynamics show deviations from the deterministic predictions. Fluctuation effects observed in the vicinity of bifurcations change the domains of mono- and bistability of the system. These are noise-induced transitions, already known in isothermal chemical systems. Another effect is related to the departure of particle velocity distribution from its equilibrium shape which modifies the rates of the processes. The resulting deviation from the deterministic dynamics is much stronger in the thermochemical system than in the isothermal case. The departure from partial equilibrium originating at the level of the velocity distribution also leads to changes of the bifurcation diagram. By analogy, we call this phenomenon a nonequilibrium-induced transition.