Full-dimensional automated potential energy surface development and detailed dynamics for the CHOO + NH reaction

• Published in: Physical chemistry chemical physics : PCCP 2023-10, Vol.25 (39), p.26917-26922
• Main Authors: Yin, Cangtao, Czakó, Gábor
• Format: Article
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/d3cp03469k

With the help of the ROBOSURFER program package, a global full-dimensional potential energy surface (PES) for the reaction of the Criegee intermediate, CH 2 OO, with the NH 3 molecule is developed iteratively using different ab initio methods and the monomial symmetrization fitting approach. The final permutationally-invariant analytical PES is constructed based on 23447 geometries and the corresponding ManyHF-based CCSD(T)-F12b/cc-pVTZ-F12 energies. The accuracy of the PES is confirmed by the excellent agreement of its stationary-point properties and one-dimensional potential energy curves compared with the corresponding ab initio data. The reaction probabilities and integral cross sections are calculated for the ground-state and several vibrationally excited-state reactions by quasi-classical trajectory simulations. Remarkable is that the maximum impact parameter b where reactivity vanishes is almost independent of collision energy ranging from 1 to 40 kcal mol −1 , and the reaction probability increases with increasing collision energy for this negative-barrier reaction. At the same time, a slight mode-specificity effect is observed. In addition, the deuterium effect is investigated and the sudden vector projection is discussed. An analytical PES is constructed by fitting 23447 ManyHF-based CCSD(T)-F12b/cc-pVTZ-F12 energies and QCT simulations are performed at collision energies ranging from 1 to 40 kcal mol −1 for the reaction of the Criegee intermediate CH 2 OO with NH 3 .