Making thermal rate constant calculations reliable using best practices: case study of OH + HBr $\to$ Br + H$_2$O

In the present work we apply the combination of Moment Tensor Potential (MTP) and Ring Polymer Molecular Dynamics (RPMD) to the calculation of the thermal rate constants of the OH + HBr $\to$ Br + H$_2$O chemical reaction at different temperatures. The MTP was parameterized using the active learning (AL) algorithm to the data obtained with the spin-unlimited method of explicitly correlated coupled clusters with allowance for double and partial allowance for triple excitations (UCCSD(T)-F12a). The considered elementary reaction represents a significant challenge for dynamics simulations due to a light atom transfer along a non-trivial reaction energy path. We compare thus obtained RPMD-AL-MTP rate constants with the ones obtained previously using the quasi-classical trajectories (QCT) and the POTLIB potential energy surface (PES) as well as with the experimental rate constants. We demonstrate that the RPMD rate constants are systematically closer to the experimental rate constants than the QCT ones. We conclude that the proposed methodology based on combining the best practices for electronic structure calculations, PES construction and dynamic simulations makes theoretical estimation of thermal rate constants reliable and can be with certainty extended to more complex chemical reactions in future.