Determining Rate Coefficients for the 11-Atom Reaction via Ring Polymer Molecular Dynamics Based on a 27-Dimensional Potential Energy Surface: The Reaction between -CHCHOO and HO.

Criegee intermediates (CIs) are potentially significant oxidants and a major source of OH radicals in the troposphere. The -CHCHOO intermediate has been confirmed as a crucial component of CIs in the atmospheric environment. Although previous studies have provided some experimental and theoretical rate constants, inconsistencies among these data remain, and the experimental data do not cover the full range of temperatures present in the troposphere. Here, we developed an accurate full-dimensional (27-dimensional) potential energy surface (PES) for the -CHCHOO + HO reaction using the fundamental invariant-neural network approach and performed the ring polymer molecular dynamics (RPMD) calculations on the basis of this PES for this complex multichannel reaction involving 11 atoms, posing a significant challenge due to current computational limits. The RPMD rate coefficients between 250 and 350 K are ∼1 order of magnitude larger than the results based on variational transition-state theory. This discrepancy highlights pronounced dynamical effects and moderate quantum effects across the two hydrogen-transfer channels. This work provides reliable rate coefficients for the title reaction, which are vital for evaluating the atmospheric fate of -CHCHOO and for developing reliable atmospheric models.