Termination of Computer-Generated Reaction Mechanisms: Species Rank-Based Convergence Criterion

The issue of the termination or truncation of computer-generated reaction models is addressed. The product rank of each species, a quantitative measure of the order in which a product appears in a reaction mechanism, was tallied during generation of the reaction mechanism. Incorporation of product rank in the convergence criterion allowed generation of reaction mechanisms for reactants and conditions that previously exhausted available memory when only the maximum carbon count was specified. A rank-based convergence criterion alone resulted in generation of infinite reaction mechanisms when radical addition reactions were considered. The rank-based criterion combined with an upper bound on the atom count of radical species capped the number of addition reactions that occurred. Coupling these two criteria provided the best capability for predicting reactant conversion and major and minor product yields with the fewest number of excess components. Inherently convergent reaction networks require no external convergence criteria.