Methods for exploring reaction space in molecular systems

The area of reaction mechanism discovery simulation has taken considerable strides in recent years. Novel methods that make hypotheses for elementary steps and complementary means for reaction path and transition state (TS) optimization are lowering the amount of chemical intuition and user effort required to explore reaction networks. The resulting networks lead from reactants to reactive intermediates and products, and are becoming closer representations of physical mechanisms involved in experiments. This review describes several of these approaches, which are categorized based on their overarching TS finding strategies. Future advances are discussed that may revolutionize the ability of simulation to fully predict not just the reaction mechanism but reaction outcomes. For further resources related to this article, please visit the WIREs website.