This theoretical/computational work aims at elucidating the stochastic kinetics and eventual equilibrium state of elementary reactions involving a small number of spatially confined molecules. The modeling is based on chemical master equation solved using the Gillespie algorithm, which is a variant of dynamic Monte Carlo simulations. The behavior of the system reaching equilibrium conditions agrees with statistical mechanics predictions published by us previously (termed "nanoconfinement entropic effect on chemical equilibrium", NCECE). It is shown that both effects can be accounted for by thermal fluctuations in the number of product molecules in the small closed system, thus providing a distinct physicochemical insight into the processes. Compared to the deterministic kinetics characteristic of macroscopic systems, and depending on the reaction thermicity, acceleration or deceleration of the stochastic kinetics is predicted for addition and exchange bimolecular reactions. Moreover, it is found that the stochastic kinetic effect can temporarily exceed the NCECE in magnitude of the extra product formation. Quite remarkably, the effect is amplified in the case of a pair of nanoconfined consecutive exchange reactions, and a rule of combining their equilibrium constants is proposed.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Energy (all)
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films