Automated transition state theory calculations of abstraction reactions by hydroperoxyl, compared to literature model values

摘要

Combustion reaction rates are determined in a variety of ways, experimental, theoretical, and heuristic, resulting in discrepancies between reaction rates that cause variations in kinetic models. We present a fully automated method to compare reaction rates for hydrogen abstraction by hydroperoxyl radicals (OOH). This workflow gathers published mechanisms from the literature, identifies the species involved, searches through them for hydrogen abstraction reactions by OOH radicals, calculates the reaction rates using an automatic transition state theory (TST) method, and compares the results. The automated TST method combines transition state geometry prediction based on group-additive interatomic distances, saddle-point geometry optimization with DFT, intrinsic reaction coordinate calculations, and a canonical transition state theory calculator, to calculate the reaction rates of these hydrogen abstraction reactions. Hydrogen abstraction reactions by OOH radicals represent one of the primary mechanisms that drive combustion reactions and accurately estimating their reaction rates facilitates the understanding behind novel fuel combustion.