Thermochemical and kinetic studies of hydrogen abstraction reaction from C16H10 isomers by H atoms

Abstract

Ab initio calculations were used to derive thermochemical and kinetic properties of the hydrogen abstraction reaction from C16H10 isomers (pyrene, fluoranthene, aceanthrylene, and acephenanthrylene) by H atoms. The study of these reactions is very important to better understand the soot formation processes. The structural properties of all studied species were optimized using the B97D3/6-311++G(d,p) level of theory. The reaction energies and barrier heights were evaluated using several density functional theory methods (B97D3, B3LYP, and M06-2X) and compared to highly-correlated ab initio wave functions within the UCCSD(T)-F12 approach. It was shown that the UCCSD(T)-F12 computational protocol can be used with such large systems to provide more accurate results compared to DFT calculations. Reliable rate constants were obtained using the Transition State Theory with Eckart's tunnelling correction over the temperature range of 250–2500 K. The influence of the structure and the position of the hydrogen abstraction CH sites of C16H10 isomers on the energetics and the rate constant were discussed and compared with available literature data.