Juan P. Senosiain

Reactions over Multiple, Interconnected Potential Wells: Unimolecular and Bimolecular Reactions on a C3H5 Potential †

In this article we analyze quantitatively and discuss in detail a number of reactions that take place on a C3H5 potential. These reactions include the reaction of hydrogen atoms with allene and propyne, the reaction of methyl with acetylene, the isomerization of cyclopropyl to allyl, and the dissociation of allyl, 1-propenyl, and 2-propenyl. The theory employs high-level electronic-structure methods to characterize the potential energy surface, RRKM theory to calculate microcanonical, J-resolved rate coefficients, and master-equation methods to determine phenomenological rate coefficients, k(T,p). The agreement between our theory and the experimental results available is very good. The final theoretical results are cast in a form that is convenient for use in chemical kinetics modeling.

Use of quantum methods for a consistent approach to combustion modelling: Hydrocarbon bond dissociation energies

An attempt has been made to use modern quantum methods to codify the data base concerning bond dissociation energies in hydrocarbons. Calculations have been performed using two hybrid DFT methods, the well-known B3LYP formalism and a newly developed alternative named KMLYP. CBS-Q has also been employed where possible. The combination of experimental uncertainty and theoretical limitations is less than completely satisfactory. However, within uncertainties that translate to a factor of two at 1500 K, many transferable quantities are elucidated. A hybrid method has been developed for the correction of DFT calculations using group additivity. Given that the philosophy behind this work is the understanding that all data bases must be optimised for specific applications, so that avoidance of large errors is more important than absolute precision, the results appear to be quite useful. We are particularly encouraged by the performance of the KMLYP method, given its ease of application to molecules of practical interest.