An accurate full-dimensional potential energy surface for the reaction OH + SO → H + SO2

Abstract

In this work, we report a full-dimensional accurate potential energy surface (PES-2020) for the reaction OH + SO → H + SO₂, a prototype with deep complexes HOSO and HSO₂. About 44 700 points are calculated at the level of UCCSD(T)-F12a/aug-cc-pVTZ and fitted by the permutation invariant polynomial-neural network (PIP-NN) approach. Particular attention is paid to the treatment of the electronic structure calculation so that the UCCSD(T)-F12a/aug-cc-pVTZ method can efficiently provide a reliable description for the ground electronic state of the title reaction. Comprehensive analyses and comparison show that the only available DMBE-PES is significantly different from the new PES-2020. Dynamics simulations on this new PES-2020 show that the reactivity decreases with the increase in collision energy. The isotropic product angular distributions remain within the studied collision energy range, 1–20 kcal mol⁻¹, complying with the deep intermediates involved during the reaction process. The product energy partitioning is also analyzed. This accurate full-dimensional PES-2020 paves the way to fully understand the dynamics of the title reaction.