Direct dynamics of a large complex hydrocarbon reaction system: The reaction of OH with exo-tricyclodecane (the main component of Jet Propellant-10)

It remains a long-standing challenge to predict the reaction kinetics of large complex hydrocarbon system from first principles. Exo-tricyclo[5.2.1.0^2,6]decane, which is further called tricyclodecane and which is the major component in JP-10 aviation fuel, and therefore its reaction with hydroxyl radical is very significant. We report high-level theoretical calculations of the rate constants of tricyclodecane + OH for the first time. We show that the exchange-correlation hybrid functional M06-2X with MG3S basis set provides an accurate and efficient calculation of the barrier heights and reaction energies. A total of 20 reaction pathways for hydrogen abstractions from chair and boat tricyclodecane conformations are considered for direct dynamics. Multi-structural canonical variational transition state theory with small-curvature tunneling (MS-CVT/SCT) is adopted to calculate the rate constants of the title reaction at 200–2000 K. The theoretical results obtained using MS-CVT/SCT with curvilinear coordinates are in fairly good agreement with the experimental measurements. We also determine the branching fractions as a function of temperature and find the tertiary abstraction from tricyclodecane is dominant. This work highlights the significance of modern DFT methods for studying combustion kinetics of large fuel molecules.